Sentencia super Meteora



Thomas Aquinas

Aristotle translated by E. W. Webster
Aquinas translated by Pierre Conway, O.P. and F.R. Larcher, O.P., 1964
html by Joseph Kenny OP


  1. Aristotle's intent in this book. Enumeration of ground previously covered in preceding books, and yet to be covered in subsequent books
  2. Principles of the natural changes to be considered in this book. Their relations to each other
  3. Mutual transformation of the elements. Presence above of the heavenly body
  4. Three questions. The first, on the order of the elements is solved
  5. The remaining two questions solved
  6. Shooting stars and meteors — cause and difference
  7. Solution of problems concerning shooting stars
  8. Cause of other phenomena appearing at night, and of certain that do not
  9. The opinions of others concerning comets
  10. Refutation of these opinions
  11. Cause, time and place of the appearance of comets according to Aristotle
  12. Opinions of others on the Milky Way
  13. The Milky Clay, according to Aristotle
  14. Causes in general of phenomena generated by the moist exhalation in lower part of the air. Of rain, dew and frost
  15. The place of the generation of hail and snow
  16. The cause of the generation of rivers
  17. The duration and change of rivers


  1. Opinions of ancients on origin of sea and its saltness
  2. The sea is shown to be the natural place of all water
  3. Why the sea does not increase. Rejection of Plato's Tartarus
  4. Whether the sea always was, and always will be
  5. Saltness of the sea according to opinions of others
  6. Cause of the sea's saltness according to Aristotle
  7. On the generation of winds
  8. On the local motion of the winds
  9. On the increase and diminishing of winds
  10. South wind not from antarctic but from summer tropic
    by unknown author:
  11. De ordine et contrietate ventorum
  12. De quibusdam accidentibus et effectibus ventorum
    by Thomas Aquinas:
  13. Improbantur quaedam opiniones de terraemotu
  14. Principium terraemotus iuxta Philosophum
  15. De accidentibus consequentibus terraemotum et differentiis eius
    by unknown author:
  16. Quomodo generentur tonitruum et cvoruscatio
  17. Opiniones aliorum de coruscatione et tonitruo refutantur


    by unknown author:

  1. De ecnephia et typhone
  2. De incensione et fulmine
  3. De quibusam accidentibus circa halo, iridem, prelios et virgas
  4. De halo
  5. De generatione colorum iridis in generali, de colore puniceo
  6. Absolvitur quaestio de coloribus iridis, quaestiones circa iridem
  7. De figura et quibusdam aliis accidentibus iridis
  8. De virgis et pareliis
  9. De fossibus et metallicis


    by unknown author

  1. Prooemium
  2. De operationibus qualitatum activarum in mixto
  3. De digestione et indigestione
  4. De speciebus digestionis et indigestionis, de pepansi et omote
  5. De hepensi et molynsi
  6. De opsesi et stateusi
  7. De quimis qualitatibus passivis corporum, de duro et molli
  8. Quomodo quaenam siccantur et humectantur
  9. De quibusdam speciebus qualitatum passivarum
  10. Quae et quot sint species qualitatum passivarum
  11. De iisdem
  12. De iisdem
  13. De iisdem
  14. De qualitatibus passivis per comparationem ad corpora
  15. De qualitatibus activis per comparationem ad corpora
  16. De corporibus homoeomeris per comparationem ad passiones praedictas


Lecture 1
Aristotle's intent in this book. Enumeration of ground previously covered in preceding books, and yet to be covered in subsequent books.
Chapter 1
(338a.) Περὶ μὲν οὖν τῶν πρώτων αἰτίων τῆς φύσεως καὶ περὶ πάσης κινήσεως φυσικῆς, ἔτι δὲ περὶ τῶν κατὰ τὴν ἄνω φορὰν διακεκοσμημένων ἄστρων καὶ περὶ τῶν στοιχείων τῶν σωματικῶν, πόσα τε καὶ ποῖα, καὶ τῆς εἰς ἄλληλα μεταβολῆς, καὶ περὶ γενέσεως καὶ φθορᾶς τῆς κοινῆς εἴρηται πρότερον. 1 We have already discussed the first causes of nature, and all natural motion, also the stars ordered in the motion of the heavens, and the physical element-enumerating and specifying them and showing how they change into one another—and becoming and perishing in general.
λοιπὸν δ' ἐστὶ μέρος τῆς μεθόδου ταύτης ἔτι θεωρητέον, ὃ πάντες οἱ πρότεροι μετεωρολογίαν ἐκάλουν 2 There remains for consideration a part of this inquiry which all our predecessors called meteorology.
ταῦτα (338b.) δ' ἐστὶν ὅσα συμβαίνει κατὰ φύσιν μέν, ἀτακτοτέραν μέντοι τῆς τοῦ πρώτου στοιχείου τῶν σωμάτων, περὶ τὸν γειτνιῶντα μάλιστα τόπον τῇ φορᾷ τῇ τῶν ἄστρων, οἷον περί τε γάλακτος καὶ κομητῶν καὶ τῶν ἐκπυρουμένων καὶ κινουμένων φασμάτων, 3 It is concerned with events that are natural, though their order is less perfect than that of the first of the elements of bodies. They take place in the region nearest to the motion of the stars. Such are the milky way, and comets, and the movements of meteors.
ὅσα τε θείημεν ἂν ἀέρος εἶναι κοινὰ πάθη καὶ ὕδατος, 4 It studies also all the affections we may call common to air and water,
ἔτι δὲ γῆς ὅσα μέρη καὶ εἴδη καὶ πάθη τῶν μερῶν, ἐξ ὧν περί τε πνευμάτων καὶ σεισμῶν θεωρήσαιμεν ἂν τὰς αἰτίας (339a.) καὶ περὶ πάντων τῶν γιγνομένων κατὰ τὰς κινήσεις τὰς τούτων ἐν οἷς τὰ μὲν ἀποροῦμεν, τῶν δὲ ἐφαπτόμεθά τινα τρόπον 5 and the kinds and parts of the earth and the affections of its parts. These throw light on the causes of winds and earthquakes and all the consequences the motions of these kinds and parts involve. Of these things some puzzle us, while others admit of explanation in some degree.
ἔτι δὲ περὶ κεραυνῶν πτώσεως καὶ τυφώνων καὶ πρηστήρων καὶ τῶν ἄλλων τῶν ἐγκυκλίων, ὅσα διὰ πῆξιν συμβαίνει πάθη τῶν αὐτῶν σωμάτων τούτων. 6 Further, the inquiry is concerned with the falling of thunderbolts and with whirlwinds and fire-winds, and further, the recurrent affections produced in these same bodies by concretion.
διελθόντες δὲ περὶ τούτων, θεωρήσωμεν εἴ τι δυνάμεθα κατὰ τὸν ὑφηγημένον τρόπον ἀποδοῦναι περὶ ζῴων καὶ φυτῶν, καθόλου τε καὶ χωρίς σχεδὸν γὰρ τούτων ῥηθέντων τέλος ἂν εἴη γεγονὸς τῆς ἐξ ἀρχῆς ἡμῖν προαιρέσεως πάσης. 7 When the inquiry into these matters is concluded let us consider what account we can give, in accordance with the method we have followed, of animals and plants, both generally and in detail. When that has been done we may say that the whole of our original undertaking will have been carried out.
Sicut in rebus naturalibus nihil est perfectum dum est in potentia, sed solum tunc simpliciter perfectum est, quando est in ultimo actu; quando vero medio modo se habens fuerit inter puram potentiam et purum actum, tunc est quidem secundum quid perfectum, non tamen simpliciter; sic et circa scientiam accidit. Scientia autem quae habetur de re tantum in universali, non est scientia completa secundum ultimum actum, sed est medio modo se habens inter puram potentiam et ultimum actum. Nam aliquis sciens aliquid in universali, scit quidem aliquid eorum actu quae sunt in propria ratione eius: alia vero sciens in universali non scit actu, sed solum in potentia. Puta, qui cognoscit hominem solum secundum quod est animal, solum scit sic partem definitionis hominis in actu, scilicet genus eius: differentias autem constitutivas speciei nondum scit actu, sed potentia tantum. Unde manifestum est quod complementum scientiae requirit quod non sistatur in communibus, sed procedatur usque ad species: individua enim non cadunt sub consideratione artis; non enim eorum est intellectus, sed sensus. 1. Just as in natural things nothing is perfect so long as it is in potency, but is perfect absolutely only when it is in ultimate act, and just as, when it is midway between pure potency and pure act, it is perfect in a qualified sense but yet not absolutely so too with science. Now the science which one has of a thing only in a universal way is not science complete according to ultimate act, but is midway between pure potency and ultimate act. For someone who knows something in a universal way, does indeed know something in act of the things that are included in its proper notion; but he who thus knows in a universal way, knows other things, not actually, but in potency only. For example, one who knows man only accordingly as he is animal, thus knows in act only a part of the definition of man, namely, the genus; but the differences constitutive of the species he does not yet know in act but potentially only. Consequently, it is plain that the completion of science requires that one not stop at what is common but go on to the species (individuals not falling under the consideration of art, since of them there is not intellectual understanding but sense knowledge).
Quia igitur Aristoteles in libro de generatione determinavit de transmutationibus elementorum in communi, necessarium fuit ad complementum scientiae naturalis, determinare de speciebus transmutationum quae accidunt circa elementa: et de his determinat in hoc libro, qui intitulatur Meteorologicorum. 2. For this reason, since Aristotle in the book, On Generation, has determined concerning the transmutation of elements in common, it was necessary, for the completion of natural science, to determine concerning the species of transmutations that affect the elements. And he determines concerning these in this book, entitled Meteorology.
Est igitur intentio eius in hoc libro determinare de transmutationibus quae accidunt circa elementa, secundum singulas species. Et ad manifestandam suam intentionem, praemittit prooemium. In quo tria facit: It is his intention, therefore, in this book to determine concerning the transmutations that occur with respect to the elements, according to their several species. And in order to indicate his intention he presents an introduction, in which he does three things:

primo enim enumerat ea de quibus tractatum est in libris scientiae naturalis praecedentibus hunc librum;

secundo manifestat de quibus in hoc libro sit agendum, ibi: reliqua autem pars huius etc.;

tertio ostendit de quibus in sequentibus libris restat agendum, ibi: pertranseuntes autem de his et cetera.

First, he enumerates the things already treated in the books of natural science that precede this book, at 3;

Secondly, he shows what is to be treated in this book, at 4;

Thirdly, he shows what remains to be discussed in books that follow, at 9.

Praecedunt autem hunc librum, secundum ordinem, in scientia naturali tres libri. Unde tria facit. 3. Three books precede the present one, according to order, in natural science. Hence he does three things [1].
Primo ponit de quo sit actum in libro physicorum. In quo quidem, quantum ad duos primos libros eius, agitur de causis naturae: et hoc tangit, concludens ex determinatione praecedentium librorum, cum dicit: de primis quidem igitur causis naturae; ut intelligantur primae causae naturae prima principia, quae sunt materia, forma et privatio, et etiam quatuor genera causarum, scilicet materia, forma, agens et finis, in sequentibus autem libris physicorum agitur de motu in generali: et hoc est quod subdit: et de omni motu naturali. First, he states what was treated in the book of Physics. As to the first two books, it is question of the causes of nature. This he alludes to, concluding from what has been determined in the books preceding [The Meteorology], when he says: "We have already spoken about the first causes of nature," meaning by "first causes of nature," the first principles, which are matter, form and privation, as well as the four genera of causes, namely, matter, form, agent and end. In the subsequent books of the Physics the discussion is of motion in general; hence he adds, "and of every natural motion."
Secundus scientiae naturalis liber est liber de caelo et mundo. In cuius prima parte, scilicet in duobus eius primis libris, agitur de caelo et stellis, quae moventur motu circulari: et quantum ad hoc dicit: adhuc autem de secundum superiorem lationem perornatis astris; perornatis, idest valde ornate dispositis, secundum superiorem lationem, idest secundum motum circularem, quo moventur omnia corpora caelestia. In secunda autem parte huius libri, scilicet tertio et quarto libro, determinat de numero elementorum et de motu locali eorum: et quantum ad hoc dicit: et de elementis corporalibus, quot et quae sint. Dicit autem elementa corporalia, ad differentiam primorum principiorum, scilicet materiae et formae, quae non sunt corpora, sed corporum elementa seu principia: ignis autem et aqua et terra corpora sunt, et sunt aliorum corporum elementa. The second book of natural science is the book, On the Heavens, in the first part of which, i.e., in its first two books, the discussion is about the heaven and the stars, which are moved with circular motion. This he alludes to when he says: "We have also discussed the superior movement of the well-appointed stars," meaning by "well-appointed," very beautifully arranged, and by "as to their superior motion," the circular motion by which all the heavenly bodies are moved. In the second part of that book, i.e. in the third and fourth books, he determines concerning the number of elements and their local motion. Alluding to this he says: "and about the bodily elements we have discussed their number and nature." He says "bodily" elements to distinguish them from the first principles, namely, matter and form, which are not bodies but the elements or principles of bodies, whereas fire and water and earth are bodies, and are the elements of other bodies.
Tertius liber scientiae naturalis est liber de generatione: in quo determinat de permutatione elementorum in invicem, in secundo libro, et de generatione et corruptione in communi in primo libro. Et hoc tangit consequenter, cum dicit: et de ea quae invicem et cetera. The third book of natural science is the book, On Generation, wherein are treated the mutual transmutation of elements, in the second book; and generation and corruption in common, in the first book. This he subsequently alludes to when he says: "and of things that are mutually transmutable."
Deinde cum dicit: reliqua autem pars huius etc., manifestat de quo sit in hoc agendum. Et circa hoc duo facit: 4. Then [2] he shows what is to be discussed in the present book. About this he does two things:

primo ponit nomen consuetum huius doctrinae;

secundo enumerat ea quae in hac doctrina continentur.

First, he gives the usual name for this body of doctrine, at 4;

Secondly, he enumerates the things contained in this doctrine, also at 4.

Dicit ergo primo quod reliqua pars huius methodi, idest scientiae naturalis, quam prae manibus habemus, restat adhuc consideranda, quam omnes priores philosophi vocabant meteorologiam, a meteoron, quod est excelsum vel elevatum, et logos, quod est sermo vel ratio: considerantur enim in hac doctrina ea quae in excelsis generantur, sicut stellae cadentes, stellae cometae, pluviae, nives, et alia huiusmodi. Quamvis et alia quaedam considerentur quae fiunt in imo, sicut fulmina, terraemotus, et alia huiusmodi: sed quia ea quae fiunt in alto, sunt mirabiliora et magis desiderata, ideo ab eis tota doctrina nomen accepit. He says therefore first that the remaining part of "this method," i.e. of natural science, which we have before us, is still to be treated. [What is now to be considered] is what all the earlier philosophers called "meteorology" - from meteoron which means "on high" or "elevated," and from logos, which is a "statement" or "explanation" - for in it are considered the things generated on high, such as falling stars, comets, rain, snow, and so on. This does not mean that other things, produced in the lower regions, such as lightning, earthquakes and the like, will not be discussed; but, because things generated on high are more marvelous and more desired, it is from them that this whole doctrine takes its name.
Secundo ibi: haec autem sunt etc., enumerat ea de quibus in hac doctrina consideratur. Quae videntur in quatuor distingui. Quaedam enim sunt quae fiunt in loco supremo propinquo corpori caelesti: et haec primo tangit, cum dicit: haec autem sunt, scilicet de quibus adhuc restat considerandum, quaecumque accidunt quidem secundum naturam, sed inordinatam, et casualiter, ut quidam putabant. Natura tamen inordinatior non est natura illa quae est primi elementi corporum, idest corporis caelestis; quod dicitur elementum, quia est pars totius universi corporalis, licet non veniat in compositionem corporis mixti, sicut elementa. Est autem natura secundum quam haec accidunt, inordinatior natura caelestis corporis: quia ea quae sunt in caelesti corpore, semper similiter se habent, in huiusmodi autem transmutationibus inferiorum corporum, accidit multa varietas. Propter quam quidam crediderunt quod haec non a natura, sed a casu acciderent, non considerantes quod naturaliter fiunt non solum ea quae sunt semper, sed etiam quae sunt ut in pluribus. Haec, inquam, accidunt circa locum maxime propinquum lationi astrorum, idest astris circulariter motis. Et hoc ponit ad differentiam subsequentium. Et exemplificat, dicens: puta de lacte, idest de lacteo circulo qui Galaxia dicitur, et stellis quae cometae dicuntur, et phantasmatibus, idest apparitionibus, ignitis et motis, quae dicuntur stellae cadentes. 5. Secondly [3] he enumerates the things to be considered in this doctrine. These are seen to be divided into four groups. For there are some things that are produced in the highest region, nearest to the heavenly body. Such things are, namely, those concerning which it still remains to be considered, things that happen indeed according to nature, but not an ordered nature and, as some claimed, by chance. This more irregular nature is not, however, the nature which belongs to the "first element of bodies," i.e., the celestial body, called "element," because it is a part of the whole corporeal universe, although it does not enter into the composition of mixed bodies, as do the elements. The nature according to which these things occur is more unordered than the nature of the celestial body, since the things in the celestial body always behave in the same way, whereas in the transmutations affecting the lower bodies much variation occurs. It was on this account that some have believed that these occurred, not by nature, but by chance, failing to consider that there is produced by nature, not only those things which happen always, but also those which happen for the most part. These, I say, occur in the region nearest the "carrying of the stars," i.e., the stars that are circularly moved. This he sets down to distinguish them from those that follow. As an example he mentions the "Milk," i.e., the milky circle called the "galaxy," and the stars called "comets," and the "phantoms," i.e. the apparitions, fiery and moving, called "falling stars" [meteors].
Secundo cum dicit: et quaecumque ponemus etc., enumerat ea quae sub praedictis fiunt; scilicet quaecumque ponuntur esse passiones communes aeris et aquae, quia ex materia aquea in loco aeris generantur, vaporibus in aquam transmutatis. 6. Secondly [4], he enumerates the things which take place under the foregoing; namely, all things that are posited as phenomena common to air and water - for they are produced from aqueous matter in the region of air, when vapors are changed into water.
Tertio cum dicit: adhuc autem terrae etc., enumerat ea quae in infimo sunt. Et dicit: adhuc autem oportet dicere de his quae sunt partes terrae, puta oriens, occidens, Septentrio, meridies; et quae sunt species, puta quod quaedam terra est calida et arenosa, quaedam frigida et calcata; et passiones partium terrae, puta quod quaedam est sulphurea, quaedam lapidosa, vel aliquo modo dissoluta. Ex quibus terrae rationibus considerabimus omnes causas spirituum, idest ventorum, quorum differentia attenditur secundum diversitatem terrae. Similiter de terraemotibus, quorum etiam causae assignantur ex diversa specie terrae; et de omnibus quae fiunt secundum motus horum, idest ventorum et terraemotuum. In quibus non omnia perfecte et secundum certitudinem tradere possumus, sed quaedam sub dubitatione relinquemus, ad utramque partem rationem inducentes: in quibusdam vero veritatem attingemus aliquo modo. 7. Thirdly [5], he enumerates what takes place in the lowest region and says: "We must also talk about the parts of the earth," such as east, west, north, south, "and about its kinds," for example, that some earth is hot and sandy, and some cold and compact, "and about the properties of the parts" of the earth, for example, that some are sulphurous, some stony or in some way broken up. "From this knowledge" of the earth "we shall consider all the causes of "spirits," i.e., winds, that differ according to the difference of the earth. Likewise, "of earthquakes," the causes of which are attributed to the different type of earth, "and of all things that take place according to the motions of these," i.e., of winds and earthquakes. In these matters we cannot explain everything perfectly and according to certitude, but shall let some things remain doubtful, giving reasons for both sides; but in others we shall to some degree reach the truth.
Quarto ibi: adhuc autem de fulminum casu etc., enumerat ea quae ex alto in infimum descendunt, ex ventis causata, dicens: adhuc autem dicemus de casu fulminum et typhonibus (qui dicuntur siphones), et incensionibus quae circa huiusmodi typhones accidunt, et aliis circularibus, quaecumque propter coagulationem accidunt passiones ipsorum corporum, scilicet elementorum. Dicit autem hoc, quia typhones ex materia compacta generantur cum quadam rotatione; et multa alia similia accidunt typhonibus, ex materia coagulatione compacta, cum quadam circulatione. Vel potest hoc referri ad iridem et halonem (idest circulum continentem solem et lunam et stellas), quae accidunt ex reverberatione radiorum ad aliquam materiam spissam. 8. Fourthly [6], he enumerates the things which descend from on high as the result of winds. He says, therefore, that we shall also give an account of the falling of thunderbolts, and of whirlwinds (called "siphons") and of the burnings that accompany such whirlwinds, and of other circular phenomena that occur from congealing and are properties of those bodies, namely, the elements. He says this because whirlwinds are generated from compacted matter set rotating, and many other like things happen to whirlwinds as a result of matter compacted and set in circular motion. Or this could refer to the rainbow and halo (i.e., the corona surrounding the sun and moon and stars) which result from rays rebounding from thick matter.
Deinde cum dicit: pertranseuntes autem de his etc., ponit de quo restat agendum in libris sequentibus. Et dicit quod postquam pertransiverimus de his quae dicta sunt, tunc speculabimur, secundum nostrum posse, modo inducto in libris praecedentibus, scilicet non tantum recitando opiniones aliorum sed etiam causas inquirendo, de animalibus et plantis, et in universali et secundum singulas species. Et tunc fere erit finis scientiae naturalis, quam a principio elegimus tradere. Dicit autem fere, quia non omnia naturalia ab homine cognosci possunt. 9. Then at [7] he mentions what remains to be treated in the books to follow and says that after we shall have finished with these matters enumerated above, we shall to the best of our ability, according to the method employed in earlier books (i.e., not by merely reciting others' opinions, but by inquiring into causes, speculate about animals and plants, both in a universal way and according to the individual species. And that will be almost the end of the natural science which we chose to discuss from the beginning. He says "almost," because not all natural things can be known by man.

Lecture 2
Principles of the natural changes to be considered in this book. Their relations to each other
Chapter 1 cont.
ὧδ' οὖν ἀρξάμενοι λέγωμεν περὶ αὐτῶν πρῶτον. After this introduction let us begin by discussing our immediate subject.
Chapter 2
ἐπειδὴ γὰρ διώρισται πρότερον ἡμῖν μία μὲν ἀρχὴ τῶν σωμάτων, ἐξ ὧν συνέστηκεν ἡ τῶν ἐγκυκλίως φερομένων σωμάτων φύσις, ἄλλα δὲ τέτταρα σώματα διὰ τὰς τέτταρας ἀρχάς, ὧν διπλῆν εἶναί φαμεν τὴν κίνησιν, τὴν μὲν ἀπὸ τοῦ μέσου τὴν δ' ἐπὶ τὸ μέσον τεττάρων δ' ὄντων τούτων, πυρὸς καὶ ἀέρος καὶ ὕδατος καὶ γῆς, τὸ μὲν τούτοις πᾶσιν ἐπιπολάζον εἶναι πῦρ, τὸ δ' ὑφιστάμενον γῆν δύο δὲ ἃ πρὸς αὑτὰ τούτοις ἀνάλογον ἔχει (ἀὴρ μὲν γὰρ πυρὸς ἐγγυτάτω τῶν ἄλλων, ὕδωρ δὲ γῆς) ὁ δὴ περὶ τὴν γῆν ὅλος κόσμος ἐκ τούτων συνέστηκε τῶν σωμάτων περὶ οὗ τὰ συμβαίνοντα πάθη φαμὲν εἶναι ληπτέον. We have already laid down that there is one physical element which makes up the system of the bodies that move in a circle, and besides this four bodies owing their existence to the four principles, the motion of these latter bodies being of two kinds: either from the centre or to the centre. These four bodies are fire, air, water, earth. Fire occupies the highest place among them all, earth the lowest, and two elements correspond to these in their relation to one another, air being nearest to fire, water to earth. The whole world surrounding the earth, then, the affections of which are our subject, is made up of these bodies.
ἔστιν δ' ἐξ ἀνάγκης συνεχὴς οὗτος ταῖς ἄνω φοραῖς, ὥστε πᾶσαν αὐτοῦ τὴν δύναμιν κυβερνᾶσθαι ἐκεῖθεν ὅθεν γὰρ ἡ τῆς κινήσεως ἀρχὴ πᾶσιν, ἐκείνην αἰτίαν νομιστέον πρώτην. 9 This world necessarily has a certain continuity with the upper motions: consequently all its power and order is derived from them. (For the originating principle of all motion is the first cause.

πρὸς δὲ τούτοις ἡ μὲν ἀίδιος καὶ τέλος οὐκ ἔχουσα τῷ τόπῳ τῆς κινήσεως, ἀλλ' ἀεὶ ἐν τέλει ταῦτα δὲ τὰ σώματα πάντα πεπερασμένους διέστηκε τόπους ἀλλήλων. ὥστε τῶν συμβαινόντων περὶ αὐτὸν πῦρ μὲν καὶ γῆν καὶ τὰ συγγενῆ τούτοις ὡς ἐν ὕλης εἴδει τῶν γιγνομένων αἴτια χρὴ νομίζειν (τὸ γὰρ ὑποκείμενον καὶ πάσχον τοῦτον προσαγορεύομεν τὸν τρόπον), τὸ δ' οὕτως αἴτιον ὅθεν ἡ τῆς κινήσεως ἀρχή, τὴν τῶν ἀεὶ κινουμένων αἰτιατέον δύναμιν. 10 Besides, that element is eternal and its motion has no limit in space, but is always complete; whereas all these other bodies have separate regions which limit one another.) So we must treat fire and earth and the elements like them as the material causes of the events in this world (meaning by material what is subject and is affected), but must assign causality in the sense of the originating principle of motion to the influence of the eternally moving bodies.

Completo prooemio, in quo philosophus suam intentionem manifestavit, hic incipit procedere ad suum propositum ostendendum. Et dividitur in duas partes: 10. Having completed an introduction, in which the Philosopher has revealed his intention, he now begins to show his proposition. And this is divided into two parts:

in prima resumit ea quae sunt necessaria ad cognoscendum principia transmutationum de quibus in hoc libro tractaturus est;

in secunda incipit de eis tractare, ibi: resumentes igitur eas et cetera.

In the first he restates facts necessary for knowing the principles of the transmutations to be treated in this book, at 11;

In the second part he begins to treat of them (L. 3).

Circa primum duo facit: About the first he does two things:

primo enumerat principia harum transmutationum, et differentiam eorum adinvicem;

secundo ostendit quomodo se habeant adinvicem in causando, ibi: est autem ex necessitate continuus et cetera.

First, he enumerates the principles of these transmutations and their difference from one another, at 11;

Secondly, he shows how they are related to one another in causing, at 12.

Dicit ergo primo quod prius determinatum est, tam in libro de caelo quam in libro de generatione, quod inter alia principia corporalia quae sunt principia aliorum corporum, unum est principium illorum corporum ex quibus constituitur natura corporum circulariter motorum, scilicet sphaerarum et stellarum: hoc autem principium dicit ipsam quintam essentiam, ex quo omnia huiusmodi formantur. Alia vero principia corporum inferiorum sunt quatuor, propter primas tangibiles qualitates, quae sunt principia agendi et patiendi, scilicet calidum, frigidum, humidum et siccum, quarum sunt tantum quatuor possibiles combinationes: nam calidum et siccum est ignis, calidum et humidum est aer, frigidum et humidum aqua, frigidum et siccum terra; calidum vero et frigidum, vel humidum et siccum aliquid esse, impossibile est. 11. He says therefore first [8] that it has been previously determined both in the book, On the Heavens, and in the book, On Generation, that among the other corporeal principles that are principles of other bodies there is one which is the principle of those bodies from which is constituted the nature of the bodies circularly moved, i.e., of spheres and stars. This principle, out of which all such bodies are formed, he calls the "fifth essence." The other principles, of the lower bodies, are four in number, because of the primary tangible qualities, which are the principles of acting and of being acted upon. These are the hot, cold, moist and dry, of which there are but four possible combinations: for the hot and dry is fire, the hot and moist is air, the cold and moist is water, and the cold and dry is earth (that something should be hot and cold, or moist and dry, is impossible).
Horum autem quatuor corporum sunt duo motus: unus quidem qui est a medio mundi sursum, qui est motus levium, scilicet ignis et aeris; alius autem motus est ad medium, qui est motus gravium, scilicet terrae et aquae. Et sic est triplex motus corporum: scilicet ad medium, qui est gravium; a medio, qui est levium; et circa medium, qui est corporum caelestium, quae neque sunt gravia neque levia. Of these four bodies there are two motions: one is upward from the middle [center] of the world, and this is the motion of light things, namely, fire and air; the other is to the middle [center], and this is the motion of heavy things, namely, earth and water. Accordingly, bodily motions are threefold: namely, to the middle for heavy bodies; from the middle for light bodies; and about the middle for the heavenly bodies, which are neither heavy nor light.
Levium autem et gravium est quaedam differentia. Nam aliquid est leve simpliciter, scilicet ignis, qui supereminet omnibus; aliquid autem est grave simpliciter, scilicet terra, quae subsidet omnibus; alia vero duo sunt secundum quid gravia et levia: nam aer est levis respectu terrae et aquae, gravis vero respectu ignis; aqua autem est levis respectu terrae, gravis autem respectu ignis et aeris. Et ideo haec duo ad alia duo extrema proportionaliter se habent, ut scilicet sicut aer est propinquior igni, ita aqua est propinquior terrae. Sic igitur patet quod iste mundus qui est circa terram, constat ex quatuor corporibus: et huius mundi oportet nos in hoc libro passiones considerare, quae sunt transmutationes variae in elementis inventae. But notice should be taken of the differences in light and heavy. For there is something which is absolutely light, namely, fire, which is above all the others; there is something which is absolutely heavy, namely, earth, which is under all the others. But the other two are in a certain respect heavy and light — for air is light in relation to earth and water, but heavy in relation to fire; water, on the other hand, is light with respect to earth, but heavy with respect to air and fire. Consequently, these two are proportional to the other two that are extremes, i.e., as air is nearer to fire, so water is nearer to earth. Thus it is plain that the universe around the earth consists of four bodies. This is the world chose passions — which are the various transmutations found in the elements — we must consider in this book.
Deinde cum dicit: est autem ex necessitate continuus etc., ostendit quomodo principia praedicta se habeant adinvicem in causando. Et dicit quod necessarium est quod iste mundus inferior consistat ex quatuor elementis, sic continuatis superioribus lationibus, idest corporibus circulariter motis: continuum autem hic accipit pro contiguo, ut scilicet nihil sit medium inter ea. Cuius quidem necessitatis ratio est, non solum quia impossibile est locum vacuum esse, unde corpora oportet corporibus contiguari: sed etiam propter finem, ut scilicet tota virtus inferioris mundi gubernetur a superioribus corporibus, quod non esset nisi se tangerent; oportet enim quod agens corporale tangat passum et motum ab ipso. 12. Then [9] he shows how the aforesaid principles are related to one another in causing. And he says that it is necessary for the lower world to consist of the four elements thus in continuity with the "upper movements," i.e., with the bodies circularly moved (by "continuous" he here means "contiguous," in the sense that nothing lies between them). The reason why this is necessary is not only because no empty place can exist (hence bodies must be contiguous to bodies), but also because the end requires it — the end being that the whole power of the lower world be governed by the superior bodies, and this would not be, unless they touched — for a bodily agent must touch the thing acted upon and moved by it.
Quod autem inferior mundus regatur a superioribus corporibus et moveatur, probat duabus rationibus. Quarum prima talis est. Causa movens, unde scilicet est principium motus, necesse est quod sit prima causa. Et hoc intelligitur per respectum ad causam formalem et materialem: nam materia patitur ab agente, agens autem naturaliter est prius patiente; forma etiam est effectus moventis, qui educit materiam de potentia in actum. Sed finis est prior agente, quia movet agentem: non tamen semper est prior in esse, sed solum in intentione. Manifestum est autem corpus caeleste inter naturalia esse primam causam: quod eius incorruptibilitas et nobilitas demonstrat. Oportet igitur quod corpus caeleste, respectu horum corporum inferiorum, sit causa unde principium motus. 13. That the lower world is ruled and moved by the superior bodies he proves with two arguments. The first is this: The movent cause, i.e., the originative principle of motion, is necessarily the first cause. (This is to be understood in its relation to the formal and material cause. For matter is acted upon by the agent, which is by nature prior to the patient. The form, too, is an effect of the movent, which educes matter from potency to act. But the end is prior to the agent, because it moves the agent. Yet it is not always prior in the order of existence, but [sometimes] only in the order of intention.) Now it is plain that in the sphere of natural things the heavenly body is the first cause, and this is proved from its incorruptibility and nobility. Consequently, the heavenly body, with respect to these lower bodies, must be the originative cause of motion.
Secundam rationem ponit ibi: adhuc autem etc.: quae talis est. Motus caelestis corporis est perpetuus. Et hoc apparet ex ipsa dispositione loci: nam in linea recta est accipere finem in actu, scilicet extremum ipsius lineae, in circulo vero non est accipere finem: et ideo dicit quod motus circularis non habet finem secundum locum. Et ne aliquis crederet propter hoc, quod motus circularis esset imperfectus, sicut motus rectus antequam perveniat ad finem, subiungit quod motus circularis semper est in fine: quodlibet enim signum datum in circulo est principium et finis; et motus circularis in qualibet parte ita est perfectus, sicut motus rectus quando est in fine. Sic igitur apparet ex ipsa dispositione loci, quod motui caelesti competit perpetuitas. 14. At [10] he gives the second argument, which is this: The motion of the heavenly body is perpetual. This is apparent from the very disposition of place: for in the case of a straight line, one arrives at an end in act, namely, the terminus of the line, but in the case of a circle, one does not arrive at an end. He says, therefore, that circular motion does not have an end according to place. And lest anyone conclude from this that circular motion is imperfect, on the same ground that a straight motion is imperfect before reaching its end, he adds that a circular motion is always at an end — for any point you designate on a circle is both a beginning and an end, and circular motion is as perfect at any sector as a straight motion is at its end. Therefore it is plain, from the very disposition of place, that, to heavenly motions, perpetuity is congruent.
Motus autem inferiorum corporum non possunt esse perpetui: quia inferiora corpora moventur motibus rectis, motus autem rectus non durat unus continuus nisi secundum mensuram magnitudinis rectae per quam transit; motus autem reflexus non est continuus, ut in VIII Physic. probatum est. Unde cum omnia corpora inferiora distent finitis locis abinvicem, et nullum eorum sit infinitum, ut probatum est in III Physic. et in I de caelo, necesse est quod motus eorum sint finiti, et non perpetui. Illud autem quod est perpetuum et semper, consequenter est motivum eorum quae non sunt semper. Unde elementa inferiora, scilicet ignem et terram et alia syngenea his, idest congenerabilia eis, scilicet aerem et aquam, et quae ex eis componuntur, oportet putare causas accidentium circa ipsum mundum inferiorem, ut in specie materiae, idest per modum causae materialis: quia hoc modo dicimus subiectum et patiens esse causam rerum. Sed quod est causa dictorum ut unde principium motus, idest per modum causae moventis, causandum est, idest existimandum est esse causam, eam virtutem quae est semper motorum, idest corporum caelestium, quae semper moventur: quod enim semper movetur, comparatur ad id quod non semper movetur, sicut agens ad patiens. The motions of lower bodies, on the other hand, cannot be perpetual, because such bodies are moved with rectilinear motions, and a rectilinear motion remains one and continuous only according to the measure of the rectilinear magnitude along which the motion passes, and a reflected motion is not continuous, as was proved in Physics VIII. Hence, since all the lower bodies are a finite distance from one another, and no such body is infinite, as was proved in Physics III and in On the Heavens I, their motions must be finite and not perpetual. What is perpetual and always, consequently, is the movent of those things which are not always. Wherefore the lower elements, namely, fire and earth and the others which are "syngeneous," i.e., congenerable, with them, namely, air and water, and those things which are composed out of them, must be reckoned the causes of the things occurring in the lower world, "in the line of matter," i.e., after the manner of the material cause, because that is the way we speak of a subject and a patient being a cause of things. But their cause in the sense of "originative source of motion," i.e., their cause after the manner of movent cause, must be "sustained," i.e., held, to be that power which belongs to the "always moved," i.e., to the heavenly bodies, which are always in motion — for what is always in motion is compared to what is not forever in motion as agent is compared to patient.

Lecture 3
Mutual transformation of the elements. Presence above of the heavenly body
Chapter 3
ἀναλαβόντες οὖν τὰς ἐξ ἀρχῆς θέσεις καὶ τοὺς εἰρημένους πρότερον διορισμούς, λέγωμεν περί τε τῆς τοῦ γάλακτος φαντασίας καὶ περὶ κομητῶν καὶ τῶν ἄλλων ὅσα τυγχάνει τούτοις ὄντα συγγενῆ. 11 Let us first recall our original principles and the distinctions already drawn and then explain the 'milky way' and comets and the other phenomena akin to these.
φαμὲν δὴ πῦρ καὶ ἀέρα καὶ ὕδωρ καὶ γῆν γίγνεσθαι ἐξ ἀλλήλων, καὶ ἕκαστον ἐν ἑκάστῳ (339b.) ὑπάρχειν τούτων δυνάμει, ὥσπερ καὶ τῶν ἄλλων οἷς ἕν τι καὶ ταὐτὸν ὑπόκειται, εἰς ὃ δὴ ἀναλύονται ἔσχατον. 12 Fire, air, water, earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate.
πρῶτον μὲν οὖν ἀπορήσειεν ἄν τις περὶ τὸν καλούμενον ἀέρα, τίνα τε χρὴ λαβεῖν αὐτοῦ τὴν φύσιν ἐν τῷ περιέχοντι κόσμῳ τὴν γῆν, καὶ πῶς ἔχει τῇ τάξει πρὸς τἆλλα τὰ λεγόμενα στοιχεῖα τῶν σωμάτων. 13 The first difficulty is raised by what is called the air. What are we to take its nature to be in the world surrounding the earth? And what is its position relatively to the other physical elements.
ὁ μὲν γὰρ δὴ τῆς γῆς ὄγκος πηλίκος ἄν τις εἴη πρὸς τὰ περιέχοντα μεγέθη, οὐκ ἄδηλον ἤδη γὰρ ὦπται διὰ τῶν ἀστρολογικῶν θεωρημάτων ἡμῖν ὅτι πολὺ καὶ τῶν ἄστρων ἐνίων ἐλάττων ἐστίν. 14 (For there is no question as to the relation of the bulk of the earth to the size of the bodies which exist around it, since astronomical demonstrations have by this time proved to us that it is actually far smaller than some individual stars.
ὕδατος δὲ φύσιν συνεστηκυῖαν καὶ ἀφωρισμένην οὔθ' ὁρῶμεν οὔτ' ἐνδέχεται κεχωρισμένην εἶναι τοῦ περὶ τὴν γῆν ἱδρυμένου σώματος, οἷον τῶν τε φανερῶν, θαλάττης καὶ ποταμῶν, κἂν εἴ τι κατὰ βάθους ἄδηλον ἡμῖν ἐστιν. 15 As for the water, it is not observed to exist collectively and separately, nor can it do so apart from that volume of it which has its seat about the earth: the sea, that is, and rivers, which we can see, and any subterranean water that may be hidden from our observation.)
τὸ δὲ δὴ μεταξὺ τῆς γῆς τε καὶ τῶν ἐσχάτων ἄστρων πότερον ἕν τι νομιστέον εἶναι σῶμα τὴν φύσιν ἢ πλείω, κἂν εἰ πλείω, πόσα, καὶ μέχρι ποῦ διώρισται τοῖς τόποις; 16 The question is really about that which lies between the earth and the nearest stars. Are we to consider it to be one kind of body or more than one? And if more than one, how many are there and what are the bounds of their regions?
ἡμῖν μὲν οὖν εἴρηται πρότερον περὶ τοῦ πρώτου στοιχείου, ποῖόν τι τὴν δύναμίν ἐστιν, καὶ διότι πᾶς ὁ περὶ τὰς ἄνω φορὰς κόσμος ἐκείνου τοῦ σώματος πλήρης ἐστί. καὶ ταύτην τὴν δόξαν οὐ μόνον ἡμεῖς τυγχάνομεν ἔχοντες, φαίνεται δὲ ἀρχαία τις ὑπόληψις αὕτη καὶ τῶν πρότερον ἀνθρώπων ὁ γὰρ λεγόμενος αἰθὴρ παλαιὰν εἴληφε τὴν προσηγορίαν, ἣν Ἀναξαγόρας μὲν τῷ πυρὶ ταὐτὸν ἡγήσασθαί μοι δοκεῖ σημαίνειν τά τε γὰρ ἄνω πλήρη πυρὸς εἶναι, κἀκεῖνος τὴν ἐκεῖ δύναμιν αἰθέρα καλεῖν ἐνόμισεν, τοῦτο μὲν ὀρθῶς νομίσας τὸ γὰρ ἀεὶ σῶμα θέον ἅμα καὶ θεῖόν τι τὴν φύσιν ἐοίκασιν ὑπολαβεῖν, καὶ διώρισαν ὀνομάζειν αἰθέρα τὸ τοιοῦτον ὡς ὂν οὐδενὶ τῶν παρ' ἡμῖν τὸ αὐτό οὐ γὰρ δὴ φήσομεν ἅπαξ οὐδὲ δὶς οὐδ' ὀλιγάκις τὰς αὐτὰς δόξας ἀνακυκλεῖν γιγνομένας ἐν τοῖς ἀνθρώποις, ἀλλ' ἀπειράκις. 17 We have already described and characterized the first element, and explained that the whole world of the upper motions is full of that body. This is an opinion we are not alone in holding: it appears to be an old assumption and one which men have held in the past, for the word ether has long been used to denote that element. Anaxagoras, it is true, seems to me to think that the word means the same as fire. For he thought that the upper regions were full of fire, and that men referred to those regions when they spoke of ether. In the latter point he was right, for men seem to have assumed that a body that was eternally in motion was also divine in nature; and, as such a body was different from any of the terrestrial elements, they determined to call it 'ether'. For the same opinions appear in cycles among men not once nor twice, but infinitely often.
ὅσοι δὲ πῦρ καθαρὸν εἶναί φασι τὸ περιέχον καὶ μὴ μόνον τὰ φερόμενα σώματα, τὸ δὲ μεταξὺ γῆς καὶ τῶν ἄστρων ἀέρα, θεωρήσαντες ἂν τὰ νῦν δεικνύμενα διὰ τῶν μαθημάτων ἱκανῶς ἴσως ἂν ἐπαύσαντο ταύτης τῆς παιδικῆς δόξης λίαν γὰρ ἁπλοῦν τὸ νομίζειν μικρὸν τοῖς μεγέθεσιν εἶναι τῶν φερομένων ἕκαστον, ὅτι φαίνεται θεωροῦσιν ἐντεῦθεν ἡμῖν οὕτως. εἴρηται μὲν οὖν καὶ πρότερον ἐν τοῖς περὶ τὸν ἄνω τόπον θεωρήμασι λέγωμεν δὲ τὸν αὐτὸν λόγον καὶ νῦν. (340a.) εἰ γὰρ τά τε διαστήματα πλήρη πυρὸς καὶ τὰ σώματα συνέστηκεν ἐκ πυρός, πάλαι φροῦδον ἂν ἦν ἕκαστον τῶν ἄλλων στοιχείων. 18 Now there are some who maintain that not only the bodies in motion but that which contains them is pure fire, and the interval between the earth and the stars air: but if they had considered what is now satisfactorily established by mathematics, they might have given up this puerile opinion. For it is altogether childish to suppose that the moving bodies are all of them of a small size, because they so to us, looking at them from the earth. This a matter which we have already discussed in our treatment of the upper region, but we may return to the point now. If the intervals were full of fire and the bodies consisted of fire every one of the other elements would long ago have vanished.
ἀλλὰ μὴν οὐδ' ἀέρος γε μόνου πλήρη 19 However, they cannot simply be said to be full of air either;
πολὺ γὰρ ἂν ὑπερβάλλοι τὴν ἰσότητα τῆς κοινῆς ἀναλογίας πρὸς τὰ σύστοιχα σώματα, κἂν εἰ δύο στοιχείων πλήρης ὁ μεταξὺ γῆς τε καὶ οὐρανοῦ τόπος ἐστίν οὐδὲν γὰρ ὡς εἰπεῖν μόριον ὁ τῆς γῆς ἐστιν ὄγκος, ἐν ᾧ συνείληπται πᾶν καὶ τὸ τοῦ ὕδατος πλῆθος, πρὸς τὸ περιέχον μέγεθος. ὁρῶμεν δ' οὐκ ἐν τοσούτῳ μεγέθει γιγνομένην τὴν ὑπεροχὴν τῶν ὄγκων, ὅταν ἐξ ὕδατος ἀὴρ γένηται διακριθέντος ἢ πῦρ ἐξ ἀέρος ἀνάγκη δὲ τὸν αὐτὸν ἔχειν λόγον ὃν ἔχει τὸ τοσονδὶ καὶ μικρὸν ὕδωρ πρὸς τὸν ἐξ αὐτοῦ γιγνόμενον ἀέρα, καὶ τὸν πάντα πρὸς τὸ πᾶν ὕδωρ. 20 for even if there were two elements to fill the space between the earth and the heavens, the air would far exceed the quantity required to maintain its proper proportion to the other elements. For the bulk of the earth (which includes the whole volume of water) is infinitesimal in comparison with the whole world that surrounds it. Now we find that the excess in volume is not proportionately great where water dissolves into air or air into fire. Whereas the proportion between any given small quantity of water and the air that is generated from it ought to hold good between the total amount of air and the total amount of water.
διαφέρει δ' οὐδὲν οὐδ' εἴ τις φήσει μὲν μὴ γίγνεσθαι ταῦτα ἐξ ἀλλήλων, ἴσα μέντοι τὴν δύναμιν εἶναι κατὰ τοῦτον γὰρ τὸν τρόπον ἀνάγκη τὴν ἰσότητα τῆς δυνάμεως ὑπάρχειν τοῖς μεγέθεσιν αὐτῶν, ὥσπερ κἂν εἰ γιγνόμενα ἐξ ἀλλήλων ὑπῆρχεν. 21 Nor does it make any difference if any one denies that the elements originate from one another, but asserts that they are equal in power. For on this view it is certain amounts of each that are equal in power, just as would be the case if they actually originated from one another.
ὅτι μὲν οὖν οὔτ' ἀὴρ οὔτε πῦρ συμπεπλήρωκε μόνον τὸν μεταξὺ τόπον, φανερόν ἐστι 22 So it is clear that neither air nor fire alone fills the intermediate space.
Ostenso quae sunt principia activa et quae sunt principia materialia passionum de quibus intendit tractare, incipit nunc determinare de eis. Et dividitur in partes duas: 15. Having identified which are the active principles and which the material principles of the passions which he intends to treat, he now begins to determine concerning them. And this is divided into two parts:

in prima determinat de particularibus transmutationibus elementorum quibus secundum se transmutantur;

in secunda determinat de transmutationibus eorum secundum quod veniunt in compositionem mixti, in quarto libro, ibi: quoniam autem quatuor et cetera.

In the first he determines concerning the particular transmutations of the elements, whereby they are transmuted according to themselves, at 15;

Secondly, he determines about their transmutations accordingly as they enter into composition to form a mixture, in Book IV.

Prima autem pars dividitur in duas: The first part is divided into two parts:

in prima enim determinat de transmutationibus seu passionibus elementorum quae in alto accidunt;

in secunda de his quae accidunt in infimo, et hoc in secundo libro, ibi: de mari autem et cetera.

In the first he determines concerning the transmutations or passions of the elements which occur on high;

In the second, about those which occur below, and this in Book II.

Prima autem pars dividitur in tres: The first part is divided into three parts:

in prima dicit de quo est intentio;

in secunda praemittit quaedam quae sunt necessaria ad subsequentium determinationem, ibi: dicimus itaque ignem et aerem etc.,

in tertia incipit determinare de principali proposito, ibi: his autem determinatis et cetera.

In the first he declares what his intention is;

In the second he states certain preliminaries necessary for determining what is to follow, at 16;

In the third he begins to determine concerning his main proposition (L.6).

Dicit ergo primo quod dicendum est de phantasia lactis, idest de apparitione lactei circuli, et de cometis, et de aliis omnibus huiusmodi quae sunt his syngenea, idest congenerabilia; ita tamen quod resumamus positiones a nobis positas in prioribus libris, et determinationes in eis prius determinatas, ut eis utamur ad propositum manifestandum, cum opus fuerit. He says therefore first [11] that we must speak of the "image of the milk," i.e., of the appearance of the milky circle, and of comets and of all other like things which are "syngeneous," i.e., generable along with them; but in doing so we shall [first] recall the positions laid down by us in the earlier books and the determinations already determined therein, so that we may, when necessary, use them to manifest the proposition.
Deinde cum dicit: dicimus itaque ignem et aerem etc., praemittit quaedam quae sunt necessaria ad subsequentia. Et circa hoc duo facit: 16. Then [12] he sets forth certain things needed for what is to follow. About this he does two things:

primo praemittit aliquid quod pertinet ad transmutationem elementorum adinvicem;

secundo dicit de ordinatione eorum in mundo, et specialiter de aere, ibi: primum quidem igitur dubitabit et cetera.

First, he premises something pertaining to the mutual transmutation of the elements, at 16;

Secondly, he speaks of the arrangement of the elements in the world, with special emphasis on air, at 17.

Dicit ergo primo quod ignis et aer et aqua et terra fiunt ex invicem, quamvis Empedocles contrarium senserit: et hoc resumit ut probatum in II de Generat. Et huius rationem assignat, quia unumquodque elementorum est in alio in potentia; et quae sic se habent, adinvicem generari possunt. Ulterius huius rationem assignat, quia communicant in una materia prima, quae eis subiicitur, et in quam sicut in ultimum resolvuntur: omnia enim quorum materia est una communis, sic se habent quod unum eorum est potentia in alio; sicut cultellus est potentia in clavi, et clavis in cultello, quia utriusque materia communis est ferrum. He says therefore first [12] that fire and air and water and earth are produced from one another (even though Empedocles thought the contrary). And he restates this as proved in On Generation II. The reason for this which he assigns is that each element exists potentially in another, and that things so related can be generated one from the other. He assigns a further reason, which is that they all have the same common first matter which underlies each of them and into which, as into an ultimate, they are all resolved: for all things whose matter is one and common to all are so related that any one is potentially in any other — as, for example, a knife is potentially in a nail, and a nail potentially in a knife, because they have a common matter, iron.
Deinde cum dicit: primum quidem igitur dubitabit etc., inquirit de ordine elementorum, et praecipue aeris. Et circa hoc tria facit. 17. Then [13] he inquires into the order of the elements and into the case of air in particular. About this he does three things:
Primo movet quaestionem: et dicit quod primo dubitatur circa corpus quod vocatur aer, quam naturam habeat in mundo qui ambit terram, utrum scilicet totum sit aer; et si non, quomodo ordinetur ad alia elementa. First he raises the question and says that our first problem is about the body called "air," as to what nature it has in the world surrounding the earth: i.e., is the whole air, and, if not, how it is related to the other elements?
Secundo ibi: moles quidem enim etc., proponit quaedam circa ordinem elementorum manifesta. Quorum primum est de terra: scilicet quod non est immanifestum quanta sit moles terrae, per comparationem ad magnitudines ambientes, scilicet caelestium corporum et aliorum elementorum. Iam enim apparuit per considerationes astrologicas, quod terra est multo minor quibusdam astris, et quod in comparatione ad ultimam sphaeram obtinet vicem puncti. Secondly [14], he proposes certain evident facts about the order of the elements. The first fact concerns the earth, and it is that we are not entirely ignorant of the size of the earth in comparison to the surrounding magnitudes, namely, those of the heavenly bodies and of the other elements. For it is already plain from the considerations of astronomers that the earth is much smaller than certain stars, and that it is but the size of a point in comparison to the outermost sphere.
Secundum proponit de aqua, ibi: aquae autem naturam et cetera. Et dicit quod non videmus aquam per se constantem, et separatam a corpore locato circa terram, scilicet a mari et fluminibus, quae sunt manifesta nobis, et a congregationibus aquarum, si quae sunt in profundo terrae immanifestae nobis, ut quidam posuerunt. Nec etiam contingit aquam sic congregatam esse: eo quod humidum aqueum non terminatur nisi termino alieno. The second fact he proposes is about water [15] and he says that we do not observe water to exist by itself and isolated from the body located about the earth, namely, from the sea and rivers, which we see, and from the bodies of water which some have asserted to exist hidden from us in the bowels of the earth. For it does not occur to water to be gathered together in this way — since the moistness which is water is contained by some alien terminus.
Iterum ibi: intermedium autem terrae etc., hic prosequitur quaestionem suam iam motam, qua quaerit quid est inter praedicta medium. 18. He further [16] pursues the question he raised earlier, namely, as to what is the middle between the aforesaid [i.e., the earth and the farthest stars].
Et circa hoc duo facit. About this he does two things:

Primo enim ostendit quod non totum spatium quod est a supremis stellis usque ad terram, est plenum uno aliquo corpore, scilicet igne vel aere, aut utroque; sed supra hoc est aliquod corpus praeter ista.

Secundo ostendit quomodo ad illud supremum corpus ordinentur alia corpora secundum positionem, ibi: reliquum est autem et cetera.

First, he shows [16] that it is not the case that the entire space from the highest stars to the earth is filled with some one body such as fire or air or both, but that above there is an additional body besides these;

Secondly, he shows how the other bodies are related to that highest body with respect to position (L. 4).

Circa primum sic procedit. Primo dicit quod dubium est utrum inter terram et inter astra ultima, quae dicuntur non errantia sed fixa, sit putandum esse unum corpus, secundum proprietatem naturae, vel plura: et si plura, quot sunt, et ubi terminentur secundum locum. Regarding the first he proceeds thus. First [16] he says that there is a problem whether between earth and the farthest stars, which are called "non-wandering" and "fixed," we should posit, according to what is proper to nature, one body or more than one; and if more than one, how many, and where are the boundaries of their regions?
Secundo ibi: nobis quidem igitur etc., resumit quoddam in libro de caelo determinatum: quod est, quale est, secundum virtutem, primum elementum, scilicet caeleste corpus; et quod totus ille mundus qui est circa superiores lationes, idest qui movetur motu circulari, est plenus illo corpore; omnia enim corpora caelestia ad naturam illius primi elementi pertinent. Et quia philosophi ponebant contrarium, ideo, ne sua opinio nova videretur, subiungit quod hanc opinionem non solum ipse habuit, sed fuit etiam antiqua opinio priorum hominum. Illud enim corpus quod dicitur aether, quod nos caelum dicimus, antiquam habet appellationem. 19. Secondly [17], he repeats something already determined in On the Heavens: this is the condition, as far as its power is concerned, of the first element, namely, the celestial body; and that that entire world which is "about the upper motions," i.e., which is moved with a circular motion, is filled with that body — for all the heavenly bodies pertain to the nature of that first element. And since the philosophers supposed the contrary, he therefore, lest his opinion appear novel, adds that not only did he have this opinion, but it was also an ancient opinion of earlier men. For the body which is called "aether," and which we call the "heaven," has an ancient name.
Sed Anaxagoras videtur putasse quod significaret idem quod ignis: accepit enim quod aether dicitur non propter semper currere, idest continue moveri, sed ab aethein, quod est ardere; quia superiora corpora credidit esse plena igne. Et quamvis in hoc male diceret, ut ibi probatum est, tamen hoc recte putavit, quod nomen aetheris conveniret alicui potentiae corporali quae est praeter ista corpora. Omnes enim antiqui visi sunt opinari, et determinaverunt illud corpus nominari aethera, quod semper currit, idest movetur, et quod est quoddam divinum, idest perpetuum, secundum suam naturam; tanquam illud corpus nulli corporum quae sunt apud nos, sit idem. Nec est mirum si hanc opinionem, quam nos de novo videbamur assumpsisse, etiam antiqui habuerunt: quia nos dicimus quod eaedem opiniones sunt reiteratae in hominibus, postquam desierunt propter negligentiam studii, non tantum bis vel ter, sed infinities. Hoc autem dicit secundum suam opinionem, qua putavit mundum et generationem hominum fuisse ab aeterno, ut apparet in prioribus libris: hoc enim supposito, manifestum fit quasdam opiniones et artes a quibusdam certis temporibus incoepisse; et oportet dicere quod multoties, vel magis infinities, sunt destructae, propter bella vel alias corruptiones, et iterum reinventae. But Anaxagoras seems to have supposed that it means the same as "fire" - for he took the word "aether" not to mean "always running," i.e., to be in continuous motion, but he derives it from aethein, which is "to burn," because he believed the superior bodies to be filled with fire. And although in this he spoke ill, nevertheless he was right in supposing the name "aether" to befit a corporeal potency over and above those bodies. For all the ancients are seen to have believed, and decided, that the name "aether" should be given to the body which always "runs," i.e., is always in motion, and which is a certain "divine," i.e., perpetual, something according to its nature. This they did as if that body were like no body that exists around us. Nor should it seem strange if this opinion, which we appeared to have adopted for the first time, was already held by the ancients. For we hold that the same opinions re-appear among men after dying out through neglect of study, not twice or thrice only, but an infinitude of times. Now he says this in keeping with his opinion that the world and human generation have been going on from eternity, as indicated in previous books. This being supposed, it is also plain that certain opinions and arts have begun from certain definite times; and thus it is necessary to say that these were in turn frequently, nay, an infinitude of times, destroyed by wars or other corrupting factors and again rediscovered.
Tertio ibi: quicumque autem ignem etc., ostendit quod non est unum horum corporum inferiorum, corpus quod circulariter movetur. Et circa hoc tria facit: 20. Thirdly [18], he shows that the circularly moved body is not any of the lower bodies. About this he does three things:

primo ostendit hoc quantum ad ignem;

secundo quantum ad aerem, ibi: at vero neque aere etc.;

tertio quantum ad utrumque, ibi: et etiam si duobus et cetera.

First, he shows this with respect to fire;

Secondly, with respect to air, at 21;

Thirdly, with respect to both, at 22.

Circa primum sciendum est quod aliqui putaverunt solum corpora caelestia delata, idest solem, lunam et stellas, esse naturae igneae; quod vero est inter eas, est naturae aereae: quidam vero posuerunt totum esse naturae igneae, sicut Anaxagoras dixit. With respect to the first [l8] it should be kept in mind that some have thought only the "carried" [moved] heavenly bodies, i.e., the sun, moon and stars, to have a fiery nature, and whatever exists between them to be of the nature of air; some on the other hand supposed the entire system to be of the nature of fire, as Anaxagoras said.
Dicit ergo quod quicumque posuerunt non solum corpora delata ignem purum, sed totum ambiens, scilicet omnes sphaeras; et id quod est intermedium terrae et astrorum est aer, scilicet a terra usque ad orbem lunae, et quod est desuper, totum est ignis; qui, inquam, sic dicunt, si considerarent ea quae nunc sunt sufficienter ostensa per mathematicam de magnitudinibus corporum, forte desisterent ab hac puerili opinione. Valde enim simplicis hominis est et ineruditi putare stellas esse parvas magnitudinibus, quia videntur parvae nobis tam a remotis aspicientibus. He says therefore that those who posited not only the moving bodies to be pure fire, but also the whole that surrounds them (i.e., all the spheres), and that which intervenes between earth and the stars to be air, i.e., from the earth to the moon's orb, and that whatever is above is all of it fire — whoever, I say, claim this, would, were they to consider the facts which have now been sufficiently proved by the mathematicians concerning the sizes of bodies, probably give up this childish opinion. Only a simple and unschooled person would believe that the stars are small in size just because they appear small to us looking at them from afar.
Dictum est autem de his in superioribus theorematibus, scilicet in II de caelo: sed etiam nunc eadem ratione dicemus ad destructionem praedictae positionis. Cum enim corpora astrorum et sphaerarum quasi improportionaliter excedant quantitatem terrae et eorum quae sunt circa terram, si non solum corpora stellarum constarent ex igne, sed etiam distantiae quae sunt inter eas essent plenae igne, iam olim annihilatum esset unumquodque aliorum elementorum, propter excessum ignis super ea. This matter has been already discussed in the previous reasonings, i.e., in On the Heavens II; but we shall once more destroy the aforesaid position with the same argument. For, since the bodies of the stars and spheres are immeasurably greater than the size of the earth and of the things near the earth, then, if not only the bodies of the stars were of fire, but all the area between them were full of fire, every one of the elements would have long since been annihilated by virtue of the preponderance of fire over it.
Deinde cum dicit: at vero neque aere etc., ostendit idem quantum ad aerem, dicens quod non est possibile quod istae distantiae sint plenae aere. Manifestum est enim quod adhuc quantitas aeris multum excederet aequalitatem analogiae, idest proportionis, quae debet esse communis inter elementa, ad hoc quod elementa conserventur. [Then... he shows the same with regard to air, saying that it is not possible for those distances to be full of air. For it is clear that the quantity of air would still exceed the equality of analogy - that is proportion - which should be common among the elements, so that the elements may be preserved.]
Deinde cum dicit: et etiam si duobus etc., ostendit idem quantum ad utrumque. Et circa hoc duo facit: 21. Then [19] he shows the same thing with respect to both. About this he does two things:

primo ponit rationem;

secundo excludit quandam cavillationem, ibi: differt autem nihil et cetera.

First, he gives the reason, at 22;

Secondly, he excludes a certain cavilling objection, at 23.

Dicit ergo primo quod proportio debita elementorum non servatur, si totus locus qui est medius inter terram et supremum caelum, est plenus duobus elementis, scilicet igne et aere. Quia moles terrae, in qua continetur etiam omnis aquae multitudo, quasi nulla pars est, habens proportionem ad totam magnitudinem ambientium corporum, cum ad solam ultimam sphaeram obtineat vicem puncti, secundum astronomos. Videmus autem quod, cum ex aqua per disgregationem sive rarefactionem fit aer, aut ex aere ignis, non est tam immensus excessus quantitatis. Oportet autem ad hoc quod conservetur debita proportio in elementis, quod eandem rationem, idest proportionem, habeat haec parva aqua ad aerem factum ex ipsa, et tota aqua ad totum aerem; ut videlicet quantum excedit quantitas aeris quantitatem aquae ex qua fit, tantum excedat in mundo quantitas totius aeris quantitatem totius aquae. He says therefore first [20] that the due proportion among the elements is not kept, if the entire space between the earth and the outermost heaven is full of two elements, namely, fire and air. For the bulk of the earth, in which the whole quantity of water is also contained, is as no part at all compared to the total size of the bodies surrounding it, since, according to astronomers, even if compared only to the outermost sphere, it is as a mere point. But we see that when, as a result of separation or rarefaction, air comes to be from water, or fire from air, there is not such an immense excess in size. Now it is necessary, if the due proportion prevailing among the elements is to be preserved, that this small quantity of water maintain the same "reason," i.e., proportion, to the air made from it, as is maintained between the whole of water and the whole of air. In other words, the extent to which the quantity of air exceeds the quantity of water from which it is made must be proportional to the extent that all the air in the world exceeds all the water in the world.
Deinde cum dicit: differt autem nihil etc., excludit quandam cavillationem: dicens quod nihil differt ad propositum si quis dicat, secundum opinionem Empedoclis, quod elementa non generantur ex invicem. Oportet enim, secundum eius opinionem, elementa esse aequalia proportione virtutis. Unde sic oportet quod conservetur aequalitas proportione virtutis in magnitudinibus elementorum, si non generantur ex invicem, sicut si generarentur. 22. Then [21] he refutes a certain cavilling objection and says that it is nothing against our position if someone should maintain, according to the opinion of Empedocles, that the elements are not generated from one another. For it is necessary, according to his opinion, that the elements be proportionally equal in power. Consequently, proportionate equality of power must be kept in the sizes of the elements if they are not generated one from the other, just as if they are.
Deinde recolligit quod dictum est, concludens ex dictis manifestum esse quod neque aer tantum replet medium locum qui est inter terram et supremas stellas, neque ignis: sed praeter haec duo elementa, oportet super ipsa esse corpus caeleste, quod nullum inferiorum est elementorum. 23. Then he summarizes [22] what has been said, and concludes that it is plain from the foregoing that neither does air fill the intermediate place between the earth and the highest stars, nor does fire; but, in addition to these two elements, there must be above them a heavenly body which is none of the lower elements.

Lecture 4
Three questions. The first, on the order of the elements, is solved
Chapter 3 cont.
λοιπὸν δὲ διαπορήσαντας εἰπεῖν πῶς τέτακται τὰ δύο πρὸς τὴν τοῦ πρώτου σώματος θέσιν, λέγω δὲ ἀέρα τε καὶ πῦρ, 23 It remains to explain, after a preliminary discussion of difficulties, the relation of the two elements air and fire to the position of the first element,
καὶ διὰ τίν' αἰτίαν ἡ θερμότης ἀπὸ τῶν ἄνωθεν ἄστρων γίγνεται τοῖς περὶ τὴν γῆν τόποις. 24 and the reason why the stars in the upper region impart heat to the earth and its neighbourhood.
περὶ ἀέρος οὖν εἰπόντες πρῶτον, ὥσπερ ὑπεθέμεθα, λέγωμεν οὕτω καὶ περὶ τούτων πάλιν. εἰ δὴ γίγνεται ὕδωρ ἐξ ἀέρος καὶ ἀὴρ ἐξ ὕδατος, διὰ τίνα ποτ' αἰτίαν οὐ συνίσταται νέφη κατὰ τὸν ἄνω τόπον; προσῆκε γὰρ μᾶλλον ὅσῳ πορρώτερον ὁ τόπος τῆς γῆς καὶ ψυχρότερος, διὰ τὸ μήθ' οὕτω πλησίον εἶναι τῶν ἄστρων θερμῶν ὄντων μήτε τῶν ἀπὸ τῆς γῆς ἀνακλωμένων ἀκτίνων, αἳ κωλύουσι πλησίον τῆς γῆς συνίστασθαι, διακρίνουσαι τῇ θερμότητι τὰς συστάσεις γίγνονται γὰρ αἱ τῶν νεφῶν ἀθροίσεις, οὗ λήγουσιν ἤδη διὰ τὸ σχίζεσθαι εἰς ἀχανὲς αἱ ἀκτῖνες.ἢ οὖν οὐκ ἐξ ἅπαντος τοῦ ἀέρος πέφυκεν ὕδωρ γίγνεσθαι, ἢ εἰ ὁμοίως ἐξ ἅπαντος, ὁ περὶ τὴν γῆν οὐ μόνον ἀήρ ἐστιν ἀλλ' οἷον ἀτμίς, διὸ πάλιν συνίσταται εἰς ὕδωρ. ἀλλὰ μὴν εἰ τοσοῦτος ὢν ὁ ἀὴρ ἅπας ἀτμίς ἐστι, δόξειεν ἂν πολὺ ὑπερβάλλειν ἡ τοῦ ἀέρος φύσις καὶ ἡ τοῦ ὕδατος, εἴπερ τά τε διαστήματα τῶν ἄνω πλήρη ἐστὶ (340b.) σώματός τινος, καὶ πυρὸς μὲν ἀδύνατον διὰ τὸ κατεξηράνθαι ἂν τἆλλα πάντα, λείπεται δ' ἀέρος καὶ τοῦ περὶ τὴν γῆν πᾶσαν ὕδατος ἡ γὰρ ἀτμὶς ὕδατος διάκρισίς ἐστιν. περὶ μὲν οὖν τούτων ἠπορήσθω τοῦτον τὸν τρόπον 25 Let us first treat of the air, as we proposed, and then go on to these questions. Since water is generated from air, and air from water, why are clouds not formed in the upper air? They ought to form there the more, the further from the earth and the colder that region is. For it is neither appreciably near to the heat of the stars, nor to the rays relected from the earth. It is these that dissolve any formation by their heat and so prevent clouds from forming near the earth. For clouds gather at the point where the reflected rays disperse in the infinity of space and are lost. To explain this we must suppose either that it is not all air which water is generated, or, if it is produced from all air alike, that what immediately surrounds the earth is not mere air, but a sort of vapour, and that its vaporous nature is the reason why it condenses back to water again. But if the whole of that vast region is vapour, the amount of air and of water will be disproportionately great. For the spaces left by the heavenly bodies must be filled by some element. This cannot be fire, for then all the rest would have been dried up. Consequently, what fills it must be air and the water that surrounds the whole earth-vapour being water dissolved. After this exposition of the difficulties involved,
ἡμεῖς δὲ λέγωμεν ἅμα πρός τε τὰ λεχθησόμενα διορίζοντες καὶ πρὸς τὰ νῦν εἰρημένα. τὸ μὲν γὰρ ἄνω καὶ μέχρι σελήνης ἕτερον εἶναι σῶμά φαμεν πυρός τε καὶ ἀέρος, οὐ μὴν ἀλλ' ἐν αὐτῷ γε τὸ μὲν καθαρώτερον εἶναι τὸ δ' ἧττον εἰλικρινές, καὶ διαφορὰς ἔχειν, καὶ μάλιστα ᾗ καταλήγει πρὸς τὸν ἀέρα καὶ πρὸς τὸν περὶ τὴν γῆν κόσμον. 26 let us go on to lay down the truth, with a view at once to what follows and to what has already been said. The upper region as far as the moon we affirm to consist of a body distinct both from fire and from air, but varying degree of purity and in kind, especially towards its limit on the side of the air, and of the world surrounding the earth.
φερομένου δὲ τοῦ πρώτου στοιχείου κύκλῳ καὶ τῶν ἐν αὐτῷ σωμάτων, τὸ προσεχὲς ἀεὶ τοῦ κάτω κόσμου καὶ σώματος τῇ κινήσει διακρινόμενον ἐκπυροῦται καὶ ποιεῖ τὴν θερμότητα. δεῖ δὲ νοεῖν οὕτως καὶ ἐντεῦθεν ἀρξαμένους. τὸ γὰρ ὑπὸ τὴν ἄνω περιφορὰν σῶμα οἷον ὕλη τις οὖσα καὶ δυνάμει θερμὴ καὶ ψυχρὰ καὶ ξηρὰ καὶ ὑγρά, καὶ ὅσα ἄλλα τούτοις ἀκολουθεῖ πάθη, γίγνεται τοιαύτη καὶ ἔστιν ὑπὸ κινήσεως καὶ ἀκινησίας, ἧς τὴν αἰτίαν καὶ τὴν ἀρχὴν εἰρήκαμεν πρότερον. 27 Now the circular motion of the first element and of the bodies it contains dissolves, and inflames by its motion, whatever part of the lower world is nearest to it, and so generates heat. From another point of view we may look at the motion as follows. The body that lies below the circular motion of the heavens is, in a sort, matter, and is potentially hot, cold, dry, moist, and possessed of whatever other qualities are derived from these. But it actually acquires or retains one of these in virtue of motion or rest, the cause and principle of which has already been explained.
ἐπὶ μὲν οὖν τοῦ μέσου καὶ περὶ τὸ μέσον τὸ βαρύτατόν ἐστιν καὶ ψυχρότατον ἀποκεκριμένον, γῆ καὶ ὕδωρ περὶ δὲ ταῦτα καὶ ἐχόμενα τούτων, ἀήρ τε καὶ ὃ διὰ συνήθειαν καλοῦμεν πῦρ, οὐκ ἔστι δὲ πῦρ ὑπερβολὴ γὰρ θερμοῦ καὶ οἷον ζέσις ἐστὶ τὸ πῦρ. ἀλλὰ δεῖ νοῆσαι τοῦ λεγομένου ὑφ' ἡμῶν ἀέρος τὸ μὲν περὶ τὴν γῆν οἷον ὑγρὸν καὶ θερμὸν εἶναι διὰ τὸ ἀτμίζειν τε καὶ ἀναθυμίασιν ἔχειν γῆς, τὸ δὲ ὑπὲρ τοῦτο θερμὸν ἤδη καὶ ξηρόν. ἔστιν γὰρ ἀτμίδος μὲν φύσις ὑγρὸν καὶ θερμόν, ἀναθυμιάσεως δὲ θερμὸν καὶ ξηρόν καὶ ἔστιν ἀτμὶς μὲν δυνάμει οἷον ὕδωρ, ἀναθυμίασις δὲ δυνάμει οἷον πῦρ. 28 So at the centre and round it we get earth and water, the heaviest and coldest elements, by themselves; round them and contiguous with them, air and what we commonly call fire. It is not really fire, for fire is an excess of heat and a sort of ebullition; but in reality, of what we call air, the part surrounding the earth is moist and warm, because it contains both vapour and a dry exhalation from the earth. But the next part, above that, is warm and dry. For vapour is naturally moist and cold, but the exhalation warm and dry; and vapour is potentially like water, the exhalation potentially like fire.
Postquam philosophus ostendit ignem et aerem non esse corpus caeleste, quod vocatur primum elementum sive primum corpus, nunc intendit ostendere quomodo ignis et aer se habeant ad illud primum corpus. Et circa hoc duo facit: 24. After showing that neither fire nor air is the heavenly body called "first element" or "first body," he now intends to show how fire and air are related to that first body. Concerning this he does two things:

primo movet hanc quaestionem, et duas alias necessarias ad propositum;

secundo solvit eas, ibi: nos autem dicamus et cetera.

First, he raises this question, and two others necessary for his proposition, at 24;

Secondly, he answers them, at 26.

Prima dividitur in tres, secundum tres quaestiones quas movet:

secunda incipit ibi: et propter quam causam etc.;

tertia ibi: de aere igitur et cetera.

The first is divided into three parts, according to the three questions raised:

The second begins at 25;

The third at 26.

Dicit ergo primo quod post praedicta relinquitur perscrutari de ordine aeris et ignis ad primum corpus, scilicet caeleste, ex quo ostensum est ipsum esse aliud praeter ista. He says therefore first [23] that after the above considerations there remains to be examined the relation of air and of fire to the first body, namely, the heavenly body, since it has been shown that it is something other than they.
Deinde cum dicit: et propter quam causam etc., movet secundam quaestionem: scilicet, propter quam causam a superioribus stellis causetur caliditas in his locis quae sunt circa terram. Et haec etiam quaestio habet ortum ex praemissis. Videtur enim secundum naturam esse quod simile generet sibi simile: si igitur corpus caeleste non est calidum, quia non est ignis neque aer, ut supra habitum est, remanet in dubio quomodo a corpore caelesti possit causari calor in istis inferioribus. 25. Then [24] he places the second question, namely, as to what cause is due the fact that from the upper stars heat is produced in the regions surrounding earth. This question, too, takes its rise from the foregoing considerations. For it seems to be according to nature that like should generate like: if, therefore, the heavenly body is not hot — for it is neither fire nor air, as was shown above — then there remains the problem of how heat can be caused by the heavenly body in these lower bodies.
Deinde cum dicit: de aere igitur etc., movet tertiam dubitationem, quae etiam ex praemissis ortum habet. Dixerat enim prius quod oportebat considerare quomodo sit accipienda natura aeris in universo: et hoc ideo, quia multa eorum de quibus determinaturus est, generationem habent in aere. Dicit ergo quod, sicut supra supposuimus, oportet primo aliquid dicere de aere: et sic erit dicendum de aliis duobus quaestionibus motis. 26. Then [25] he raises the third problem which also arises from the foregoing. For he had said previously that we must inquire how the nature of air in the universe is to be taken, and this for the reason that many of the things concerning which he is about to determine are generated in the air. He says therefore that, as we laid down above, we must first speak of air; then we shall have to discuss the other two questions proposed.
Unde statim incipit movere dubitationem ad naturam aeris pertinentem. Ostensum est enim in libro de Generat. quod aqua fit ex aere, et e converso. Cum autem ex condensationibus nubium generatur pluvia, hoc est aerem converti in aquam. Quaerit ergo, si aqua fit ex aere et aer ex aqua, quare in superiori parte aeris non inspissentur nubes ad generationem aquae. Hence he immediately begins to raise the difficulty on the nature of air. For it has been shown in On Generation II that water is produced from air and conversely. Thus, since the rains are generated from the condensings of the clouds, this is air being converted into water. He asks, therefore, if water comes to be from air, and air from water, why is it that, in the upper region of air, clouds are not condensed [thickened] to generate water?
Et inducit rationem ad ostendendum quod hoc fieri deberet. Manifestum est enim quod condensatio nubium fit ex frigiditate: nam sicut calidi est rarefacere, ita frigidi inspissare. Locus autem aeris qui est remotior a terra, videtur esse frigidior: quia videntur ibi cessare duae causae calefactionis. Quarum una est propinquitas ad astra, ex quibus causatur calor: et hoc tangit cum dicit quod neque ille locus aeris, superior scilicet, est sic prope astra existentia calida, scilicet secundum effectum, ut caliditas astrorum possit impedire inspissationem nubium. Alia causa calefactionis est reverberatio radiorum solis a terra: et hoc tangit cum dicit: neque iterum ille locus superioris aeris est prope radios refractos, idest reverberatos, a terra, qui prohibent congregari nubes prope terram, per hoc quod sua caliditate disgregant consistentias vaporum. Et quod haec secunda causa non impediat congregationem, manifestat per signum. Manifestum est enim quod congregationes nubium fiunt ibi, ubi radii repercussi a terra iam desinunt habere virtutem calefaciendi, propter hoc quod in immensum sparguntur, et sic multum distant a radiis cadentibus; unde non multiplicatur causa caloris. And he gives a reason to show that such a thing should happen. For it is plain that condensation of clouds is due to coldness, for just as heat causes things to rarify, so cold causes things to condense. Now it seems that a place should be colder the farther it is from earth, because in such a place the two causes of heating are lacking. One of these causes is proximity to the stars that cause heat; and this is referred to when he says that the upper region of air is not close enough to the stars which are hot, namely, as to effect, to allow the heat of the stars to prevent the thickening of clouds. The other cause of heat is solar rays bouncing back from the earth; this cause he refers to when he says that neither is that region of upper air near the rays "refracted," i.e., reverberated, from the earth, which rays prevent clouds from gathering close to the earth, inasmuch as their heat breaks down the consistency of the vapors. That this second cause does not prevent congregation he shows through a sign. For it is plain that the comings together of clouds occur where the rays reflected from the earth have already lost their power to heat through being immeasurably dispersed and are thus far distant from the rays that strike the earth; hence the cause of heat is not multiplied.
Ad huius autem intelligentiam, sciendum est quod radii procedentes a sole ad terram sunt causa caliditatis. Cum autem radius in terram cadens repercutitur, fit iterum alius radius a terra quasi resursum tendens. Quanto ergo hi duo radii fuerint magis sibi invicem propinqui, tanto plus de calore causatur: quia virtus utriusque radii, scilicet cadentis et reflexi, pertingit ad eandem partem aeris. Et inde est quod ubi radius solis cadens super terram facit angulum rectum, ibi est maximus calor, quia reflexio fit in eandem partem: quanto vero radius cadens in aliquo loco fecerit angulum maiorem recto, tanto est minus de calore; quia, cum repercussio fiat secundum pares angulos, radius repercussus, propter amplitudinem anguli, multum distat a radio primo cadente. Manifestum est autem quod quanto duae lineae continentes angulum magis procedunt, tanto magis distant abinvicem. Unde quanto magis receditur a terra, ubi fit reverberatio, tanto praedicti duo radii magis distant abinvicem, et est minor calor. Et ideo propter immensam separationem praedictorum radiorum abinvicem in loco superiori, desinit calor, et condensantur ibi nubes propter frigus. Et hoc est quod dicit: nubium congregationes fiunt ubi desinunt iam radii propter spargi in immensum. Sic igitur utraque causa quae posset impedire congregationem nubium in superiori parte aeris, cessat, ut dictum est. Et cum ibi non condensentur nubes, oportet dicere quod aqua non sit nata fieri ex omni aere: aut si similiter se habet omnis aer ad hoc quod generetur ex eo aqua, oportet quod iste aer qui est circa terram, non solum sit aer, sed sicut vapor, et ex hac causa congregetur ad generationem aquae; superior autem, qui est purus aer, non posset condensari in aquam. Sed hoc non potest esse: quia si totus iste aer qui est circa terram, cum sit tam magnus, vapor est, videtur sequi quod natura aeris et aquae multum excedat alia elementa. Quia superiores distantiae, quae scilicet sunt inter stellas, sunt plenae aliquo corpore, cum nihil sit vacuum, ut in IV Physic. probatum est: impossibile est autem quod sint plenae igne, quia sic omnia alia exsiccarentur, ut supra probatum est: relinquitur ergo quod sint plenae aere, et illud quod est circa terram sit plenum aqua. Sed hic aer est vapor: quia vapor est quaedam disgregatio aquae, idest aqua rarefacta. This last statement becomes plain if we keep in mind the fact that the rays coming from the sun to the earth are what cause heat. When a ray which comes from the sun to earth is reflected, there is now produced another ray as though moving upwards from the earth. The closer these two rays are to each other, the greater the heat produced, because the powers of both rays, i.e., that of the incident ray and that of the reflected ray, act on the same part of the air. Consequently, where a ray of the sun strikes the earth at a right angle, there a maximum of heat is produced, because the ray is reflected into the same direction; when a ray falling on some place strikes at an angle less than a right angle, the heat is by that much less, since, as repercussion takes place according to similar angles, a reflected ray, because of the wideness of the angle, is greatly distant from the ray which first falls. It is plain that the farther two lines containing an angle proceed, the greater becomes the distance between them. Hence, the farther one moves from the earth, where reflexion takes place, the farther the aforesaid two rays grow distant from each other, and there is less heat. Therefore, due to the immense separation of the aforesaid rays from one another in the upper region, the heat ceases, and clouds are formed there on account of the cold. And this what he says: "Gatherings of clouds are produced where the rays now cease because of immeasurable scatterings." Consequently, both causes that could prevent forming of clouds are absent in the upper region of air, as has been said. But since, notwithstanding this, clouds do not form there, it is necessary to spy either that water cannot be formed from just any air, or, if all air is alike so far as being convertible into water is concerned, this air near the earth must not only be air, but as a vapor, and for this reason be gathered to generate water, while the upper air, which is pure air, cannot be condensed into water. But this cannot be: for if the totality of air near the earth, since it is such a great amount, is vapor, then it is seen to follow that the nature of air and of water would far exceed the other elements. Because the higher distances, between the stars, are filled with some body (for there is no such thing as a void, as was proved in Physics IV, and they cannot be filled with fire, for this would result in everything's drying up, as was proved above, consequently they must be filled with air, while the region near the earth is filled with water. But this air is vaporous, for vapor is a certain "disjoining of water," i.e., rarefied water.
Et sic positis tribus quaestionibus, quasi colligens subdit quod de praedictis dubitatum sit hoc modo. Then, having presented the three questions, he adds, as though summarizing, that the problems concerning the aforesaid have been raised in this manner.
Deinde cum dicit: nos autem dicamus etc., solvit propositas quaestiones: 27. Then at [26] he solves the questions proposed:

et primo eam quae est de ordinatione elementorum;

secundo eam quae est de generatione nubium, ibi: eius quidem igitur etc.;

tertio eam quae est de caliditate a stellis in inferioribus causata, ibi: de facta autem caliditate et cetera.

First, the question about the order of the elements;

Secondly, the one about generation of clouds (L. 5);

Thirdly, the one about heat produced in lower bodies by the stars (L. 5).

Circa primum tria facit. Primo resumit quod dictum est de natura primi corporis: dicens quod, ad intellectum et eorum quae nunc quaesita sunt, et eorum quae postmodum sunt dicenda, oportet determinando dicere quod supremum corpus usque ad lunam est alterum ab igne et aere, sicut iam ostensum est; et quod in ipso supremo corpore est aliquid purius, et aliquid minus purum vel sincerum: non quod ibi sit aliqua compositio vel mixtio extraneae naturae; sed magis purum dicitur quod est magis nobile, magis virtuosum, magis formale. Unde et habet differentias in virtute et nobilitate: et maxime ista differentia manifesta est ex illa parte qua desinit ad aerem et ad mundum inferiorem qui est circa terram; in luna enim apparet defectus luminis, et quando est plena, apparent in ea quaedam umbrositates. Regarding the first he does three things. First, he repeats what has been said about the nature of the first body and says that for an understanding both of the matters now in question and of matters to be stated later, we must state decisively that the highest body as far as the moon is other than fire and air, as has already been proved, and that there is in that highest body something more pure, and something less pure or sincere, without implying that there is present any composition or mixture of an extraneous nature. Rather "more pure" implies more noble, more virtuous, more formal. Hence it admits of differences both in power and in nobility. This difference is especially evident where it ceases at the air and the lower world surrounding the earth, for in the moon there appear defects of light, and, when it is full, certain dark areas appear.
Secundo ibi: lato autem primo elemento etc., ostendit effectum quem habet corpus superius in inferiora. Et dicit quod primo elemento, idest caelo, circulariter moto, et motis corporibus quae sunt in ipso, idest sole et stellis, illa pars inferioris mundi quae est ei propinquior, quasi disgregata seu rarefacta per motum superioris corporis, accenditur: et sic fit caliditas. Et subiungit rationem, dicens quod hoc oportet intelligere incipiendo. 28. Secondly, at [27] he shows what effect the higher body has upon the lower ones. And he says that by means of the "first element," i.e., the heaven, circularly moved, and the bodies moved in it, namely, sun and stars, that part of the lower world nearest to it, dispersed or rarefied, as it were, by the motion of the superior body, becomes inflamed and heat is produced. And he gives the reason, saying that to understand this we must go back to the beginning.
Tota enim natura corporalis quae est sub corpore circulariter moto, est sicut quaedam materia existens in potentia ad caliditatem, frigiditatem, siccitatem et humiditatem, et ad alias passiones et formas quae consequuntur ad haec: et quia materia reducitur in actum a primo agente, natura etiam corporalis fit talis actu per hoc quod participat de motu vel non participat, sed immobilis permanet, a corpore caelesti, quod supra diximus esse causam et principium unde est motus in istis inferioribus. Non est autem intelligendum quod corpora inferiora recipiant huiusmodi passiones a superioribus tanquam accidentaliter, et non secundum naturam, sicut aqua cum calefit ab igne: sed ipsam naturam vel formam, secundum quam naturaliter sunt calida vel frigida, a superiori corpore recipiunt multo principalius quam a generante; nam primum generationis principium est corpus caeleste. For the entire bodily nature that exists under the circularly moved body is as a certain matter which is in potency to heat, cold, dryness, and wetness, and to the other passions and forms that result therefrom; and because matter is reduced to act by the first agent, bodily nature also becomes actually such and such by the fact that it participates in the motion, or does not participate but remains immobile, from the heavenly body, which we have previously declared to be the cause and originative principle of the motion in these lower bodies. This does not mean that the lower bodies receive such passions from the superior bodies, as it were, incidentally, and not according to nature, as when water becomes heated by fire; rather, the very nature or form according to which they are naturally hot or cold is received more principally from the superior body than from their generator, for the first principle of generation is the heavenly body.
Tertio ibi: in medio quidem igitur etc., ostendit ordinem elementorum. Si enim per participationem motus fit calor in istis inferioribus, et per elongationem a motu caelesti e converso fit frigus, necesse est quod illud quod est frigidissimum et gravissimum, idest aqua et terra, sit magis remotum a motu caelesti, existens in medio quantum ad terram, et circa medium quantum ad aquam. Vel dicit circa medium, eo quod medium, cum sit indivisibile, non potest esse locus corporis: sed circa medium, idest centrum mundi, est terra et aqua, centrum autem terrae est in centro totius. Circa haec autem, scilicet terram et aquam, et habita his, idest consequenter ordinata post ipsa, est aer et id quod consueto nomine vocamus ignem, in quibus abundat calor. 28 bis. Thirdly [28] he shows the order of the elements. For if heat originates in these lower bodies through participation in motion, and if, on the other hand, cold is due to distance from the heavenly motion, then, of necessity, that which is coldest and heaviest, namely, water and earth, is more removed from the heavenly motion and exists in the middle, as the earth does, or about the middle, as water does. Or else he says, "around the middle," because the middle, being indivisible, cannot be the place of a body, but rather, earth and water are "around the middle," i.e., the center of the world — for the center of the earth is in the center of the whole. "Around these," namely, earth and water, and "had to these," i.e., ordered in sequence after them, are air, and what is commonly called fire, in which [two] heat abounds.
Exponit autem quod dixerat, dicens quod quartum elementum supra aerem ordinatum non proprie vocatur ignis. Ignis enim significat excessum calidi, et est quasi quidam fervor et accensio quaedam; sicut glacies non est elementum, sed est quidam excessus frigoris ad aquam congelatam. Id autem ad quod sic se habet ignis sicut glacies ad aquam, non est nominatum, et ideo nominamus ipsum nomine ignis: sicut si aqua non haberet nomen, et nominaremus elementum aquae glaciem. He explains his statement that the fourth element, i.e., the one located above air, is not strictly called "fire." For "fire" signifies an excess of heat and is, as it were, a certain intensity and igniting. In the same way, ice is not an element but a certain superabundance of coldness producing congealed water. Now that to which fire is related in the way that ice is related to water has no name; so we call it by the name of fire. It is as though water should have no name and we should call the element of water, "ice."
Sed oportet intelligere quod de toto isto corpore quod a nobis dicitur aer, una pars, quae est propinqua terrae, est quasi calida et humida, propter id quod habet de vapore et exhalatione terrae. Sic enim elementa sunt ordinata, secundum quod eorum naturae competit: unde quia aer secundum naturam suam est calidus et humidus, sic est dispositus ut vaporem terrae suscipiat, ad eius calorem et humiditatem servandam. Sed illa pars corporis quod communiter vocatur aer, quae est superior, est calida et sicca; et hanc partem vocamus elementum ignis. Et sic aer nomen commune est duobus elementis. But we must understand that in regard to that whole body we call "air," one part, the part nearest the earth, is as though hot and moist on account of vapor, and exhalation from the earth. For the elements are arranged in a manner that befits their nature; therefore, because air is naturally hot and moist, it is disposed to receive vapor from the earth to preserve its heat and moisture. But that part of the body commonly called "air" which is higher, is hot and dry; and this upper part we call the element "fire." In this way the name "air" is common to two elements.
Et quia dixerat de vapore et exhalatione terrae, ostendit differentiam inter ea. Et dicit quod natura vaporis est esse humidum et calidum, natura autem exhalationis est esse calidum et siccum: et sic vapor, propter humiditatem, est quasi in potentia ad aquam; exhalatio autem, propter siccitatem, est quasi in potentia ut igniatur. And because he had spoken about vapor and exhalation from the earth, he shows the difference between them and says that the nature of vapor is to be moist and hot, whereas the nature of an exhalation is to be hot and dry. As a result, vapor is, on account of its moistness, in potency to water; but an exhalation, on account of its dryness is, as it were, in potency to be ignited.

Lecture 5
The remaining two questions solved
Chapter 3 cont.
τοῦ μὲν οὖν ἐν τῷ ἄνω τόπῳ μὴ συνίστασθαι νέφη ταύτην ὑποληπτέον αἰτίαν εἶναι, ὅτι οὐκ ἔνεστιν ἀὴρ μόνον ἀλλὰ μᾶλλον οἷον πῦρ. 29 So we must take the reason why clouds are not formed in the upper region to be this: that it is filled not with mere air but rather with a sort of fire.
οὐδὲν δὲ κωλύει καὶ διὰ τὴν κύκλῳ φορὰν κωλύεσθαι συνίστασθαι νέφη ἐν τῷ ἀνωτέρω τόπῳ ῥεῖν γὰρ ἀναγκαῖον ἅπαντα τὸν κύκλῳ ἀέρα, ὅσος μὴ ἐντὸς τῆς περιφερείας λαμβάνεται τῆς ἀπαρτιζούσης ὥστε τὴν γῆν σφαιροειδῆ εἶναι πᾶσαν φαίνεται γὰρ καὶ νῦν ἡ τῶν ἀνέμων γένεσις ἐν τοῖς λιμνάζουσι τόποις τῆς γῆς, καὶ οὐχ (341a.) ὑπερβάλλειν τὰ πνεύματα τῶν ὑψηλῶν ὀρῶν. ῥεῖ δὲ κύκλῳ διὰ τὸ συνεφέλκεσθαι τῇ τοῦ ὅλου περιφορᾷ. τὸ μὲν γὰρ πῦρ τῷ ἄνω στοιχείῳ, τῷ δὲ πυρὶ ὁ ἀὴρ συνεχής ἐστιν ὥστε καὶ διὰ τὴν κίνησιν κωλύεται συγκρίνεσθαι εἰς ὕδωρ, ἀλλ' ἀεὶ ὅ τι ἂν βαρύνηται μόριον αὐτοῦ ἐκθλιβομένου εἰς τὸν ἄνω τόπον τοῦ θερμοῦ κάτω φέρεται, ἄλλα δ' ἐν μέρει συναναφέρεται τῷ ἀναθυμιωμένῳ πυρί, καὶ οὕτω συνεχῶς τὸ μὲν ἀέρος διατελεῖ πλῆρες ὂν τὸ δὲ πυρός, καὶ ἀεὶ ἄλλο καὶ ἄλλο γίγνεται ἕκαστον αὐτῶν. 30 However, it may well be that the formation of clouds in that upper region is also prevented by the circular motion. For the air round the earth is necessarily all of it in motion, except that which is cut off inside the circumference which makes the earth a complete sphere. In the case of winds it is actually observable that they originate in marshy districts of the earth; and they do not seem to blow above the level of the highest mountains. It is the revolution of the heaven which carries the air with it and causes its circular motion, fire being continuous with the upper element and air with fire. Thus its motion is a second reason why that air is not condensed into water. But whenever a particle of air grows heavy, the warmth in it is squeezed out into the upper region and it sinks, and other particles in turn are carried up together with the fiery exhalation. Thus the one region is always full of air and the other of fire, and each of them is perpetually in a state of change.
περὶ μὲν οὖν τοῦ μὴ γίγνεσθαι νέφη μηδ' εἰς ὕδωρ σύγκρισιν, καὶ πῶς δεῖ λαβεῖν περὶ τοῦ μεταξὺ τόπου τῶν ἄστρων καὶ τῆς γῆς, καὶ τίνος ἐστὶν σώματος πλήρης, τοσαῦτα εἰρήσθω. 31 So much to explain why clouds are not formed and why the air is not condensed into water, and what account must be given of the space between the stars and the earth, and what is the body that fills it.
περὶ δὲ τῆς γιγνομένης θερμότητος, ἣν παρέχεται ὁ ἥλιος, μᾶλλον μὲν καθ' ἑαυτὸ καὶ ἀκριβῶς ἐν τοῖς περὶ αἰσθήσεως προσήκει λέγειν (πάθος γάρ τι τὸ θερμὸν αἰσθήσεώς ἐστιν), διὰ τίνα δ' αἰτίαν γίγνεται μὴ τοιούτων ὄντων ἐκείνων τὴν φύσιν, λεκτέον καὶ νῦν. 32 As for the heat derived from the sun, the right place for a special and scientific account of it is in the treatise about sense, since heat is an affection of sense, but we may now explain how it can be produced by the heavenly bodies which are not themselves hot.
ὁρῶμεν δὴ τὴν κίνησιν ὅτι δύναται διακρίνειν τὸν ἀέρα καὶ ἐκπυροῦν, ὥστε καὶ τὰ φερόμενα τηκόμενα φαίνεσθαι πολλάκις. 33 We see that motion is able to dissolve and inflame the air; indeed, moving bodies are often actually found to melt.
τὸ μὲν οὖν γίγνεσθαι τὴν ἀλέαν καὶ τὴν θερμότητα ἱκανή ἐστιν παρασκευάζειν καὶ ἡ τοῦ ἡλίου φορὰ μόνον ταχεῖάν τε γὰρ δεῖ καὶ μὴ πόρρω εἶναι. ἡ μὲν οὖν τῶν ἄστρων ταχεῖα μὲν πόρρω δέ, ἡ δὲ τῆς σελήνης κάτω μὲν βραδεῖα δέ ἡ δὲ τοῦ ἡλίου ἄμφω ταῦτα ἔχει ἱκανῶς. 34 Now the sun's motion alone is sufficient to account for the origin of terrestrial warmth and heat. For a motion that is to have this effect must be rapid and near, and that of the stars is rapid but distant, while that of the moon is near but slow, whereas the sun's motion combines both conditions in a sufficient degree.
τὸ δὲ μᾶλλον γίγνεσθαι ἅμα τῷ ἡλίῳ αὐτῷ τὴν θερμότητα εὔλογον, λαμβάνοντας τὸ ὅμοιον ἐκ τῶν παρ' ἡμῖν γιγνομένων καὶ γὰρ ἐνταῦθα τῶν βίᾳ φερομένων ὁ πλησιάζων ἀὴρ μάλιστα γίγνεται θερμός. καὶ τοῦτ' εὐλόγως συμβαίνει 35 That most heat should be generated where the sun is present is easy to understand if we consider the analogy of terrestrial phenomena, for here, too, it is the air that is nearest to a thing in rapid motion which is heated most. This is just what we should expect, as it is the nearest air that is most dissolved by the motion of a solid body. This then is one reason why heat reaches our world.
μάλιστα γὰρ ἡ τοῦ στερεοῦ διακρίνει κίνησις αὐτόν. διά τε ταύτην οὖν τὴν αἰτίαν ἀφικνεῖται πρὸς τόνδε τὸν τόπον ἡ θερμότης, καὶ διὰ τὸ τὸ περιέχον πῦρ τὸν ἀέρα διαρραίνεσθαι τῇ κινήσει πολλάκις καὶ φέρεσθαι βίᾳ κάτω. 36 Another is that the fire surrounding the air is often scattered by the motion of the heavens and driven downwards in spite of itself.
σημεῖον δ' ἱκανὸν ὅτι ὁ ἄνω τόπος οὐκ ἔστι θερμὸς οὐδ' ἐκπεπυρωμένος καὶ αἱ διαδρομαὶ τῶν ἀστέρων. ἐκεῖ μὲν γὰρ οὐ γίγνονται, κάτω δέ καίτοι τὰ μᾶλλον κινούμενα καὶ θᾶττον, ἐκπυροῦται θᾶττον. πρὸς δὲ τούτοις ὁ ἥλιος, ὅσπερ μάλιστα εἶναι δοκεῖ θερμός, φαίνεται λευκὸς ἀλλ' οὐ πυρώδης ὤν. 37 Shooting-stars further suffix to prove that the celestial sphere is not hot or fiery: for they do not occur in that upper region but below: yet the more and the faster a thing moves, the more apt it is to take fire. Besides, the sun, which most of all the stars is considered to be hot, is really white and not fiery in colour.
Soluta quaestione de ordinatione elementorum, solvit quaestionem de inspissatione nubium. Et ponit duas solutiones. Quarum primam concludit ex praedictis, dicens quod hanc existimandum est esse causam quare in superiori parte aeris non congregantur nubes, quia pars eius superior, quae communiter vocatur aer, non solum est aer, sed magis est quasi ignis, ut dictum est. Sed quia etiam multo inferius infra illam partem adhuc non generantur nubes, necesse fuit ut poneret aliam solutionem. 29. Having solved the question about the order of the elements, he now solves the one about the thickenings which produce clouds. And he gives two solutions, the first of which he derives from the foregoing [29], saying that the cause why clouds are not formed together in the upper region of the air must be considered to be the fact that this upper region, which is commonly called "air," is not only air but is something more akin to fire, as has been said. But because clouds are not formed even much below this region, it was necessary to present another solution.
Unde secundam solutionem ponit ibi: nihil autem prohibet et cetera. Et dicit quod nihil prohibet etiam propter motum aeris in circuitu, prohiberi quod nubes non congregentur in superiori loco: quia necessarium est quod totus aer qui est in circuitu terrae, fluat circulariter motus. Sed ab isto fluxu excipit illum aerem qui capitur inter peripheriam, idest circumferentiam, definitam, idest quae continetur infra partes terrae, ut sic tota terra inveniatur esse sphaerica cum aere incluso inter partes terrae. Et sic ille aer qui excedit omnem altitudinem montium, in circuitu fluit: aer autem qui continetur infra montium altitudinem, impeditur ab hoc fluxu ex partibus terrae immobilibus. 30. Hence he presents a second solution [30] and says that nothing prevents the air's motion in its circuit from inhibiting the gathering of clouds in the upper region; for it is necessary that all the air on the circumference of the earth flow with a circular motion. But he does not include in that flow the air trapped inside the "defined periphery," i.e., the circumference, namely, air enclosed within the parts of the earth, thus making a perfect sphere by virtue of the air enclosed between the parts. Therefore that air exceeding the height of all mountains flows in an orbit, while the air contained below the heights of the mountains is prevented from this flowing, blocked by the immovable parts of the earth.
Et propter hoc generatio ventorum videtur esse nunc in locis terrae stagnantibus, idest in aere qui continetur infra partes terrae, ac si essent stagna aeris quiescentis. Si enim aer in quo generantur venti, moveretur circulariter, oporteret quod omnes venti cum eo circulariter circumferrentur: nunc autem videmus ex diversis partibus ventos flare. Et quia in aere fluenti non generantur venti, sed in quiescenti, propter hoc venti non excedunt montes altos: dicitur enim ab antiquis quod, sacrificiis factis in altissimis montibus, post annum inveniebatur cinis adhuc salvus, in eodem loco manens. Et hoc quod venti non generantur ibi, est signum quod etiam nubes ibi non condensantur in pluvias. Quare autem aer qui excedit montes fluat, ostendit, subdens quod ideo fluit in circuitu, quia simul trahitur cum circulatione caeli: ignis enim est continuus, idest contiguus, cum corpore caelesti, aer autem cum igne. This is the reason why winds seem now to be generated "in stagnant areas of the earth," i.e., in air which is trapped between the parts of the earth, as though constituting pools of still air. For if the air where winds are born were moved circularly, it would be necessary that all winds accompany it along its circular orbit; but now we observe that winds blow out of diverse regions. And because winds are born not in the flowing air, but in the still air, they never exceed the high mountains; for it is said by the ancients that, when sacrifices were made on the loftiest mountains, the ashes, a year later would be found still in the same place intact. The fact that winds are not generated there is a sign, too, that clouds are not condensed into rain there. But why the air above the mountains flows he explains by saying that the reason it flows along in its course is that it is drawn along by the circling of the heaven; for fire is "continuous," i.e., contiguous, with the heavenly body, and air with fire.
Quia ergo superior aer fluit, per eius motum prohibetur congregari in aquam: quia motus rarefacit et congregationem impedit. Sed si qua pars illius aeris aliquo modo condensetur, aut aliquod spissum aliquo modo feratur per aliquam violentiam, feretur deorsum, idest in locum aeris propinqui terrae: et si quid calidum erat in ea, feretur sursum. Et alia pars illius aeris, quae non gravatur, feretur sursum simul cum igne exhalato. Et sic, dum eorum quae resolvuntur a terris et aquis aliquid manet in loco aeris, aliquid autem fertur ad locum ignis, continue unus locus manet plenus aere, et alius plenus igne: non tamen ita quod semper maneat idem aer et ignis numero incorruptus; sed semper, corrupta una parte aeris vel ignis, vel per violentiam ad terram expulsa, generatur alia, quae sursum a terra et aqua elevatur. Et ita, licet semper maneat in loco aeris aer, et in loco ignis ignis, tamen semper unumquodque ipsorum fit aliud et aliud per continuam generationem et corruptionem; sicut in fluvio decurrenti patet, in quo semper manet aqua, non tamen eadem numero, sed una defluente et alia succedente. Therefore, because the upper air flows along, its motion prevents its being gathered into water, for movement rarefies things and prevents coalescence. But whenever a portion of that air condenses in some way, something denser is carried along in some way by some constrained motion, it will be carried downward, i.e., to the place of the air close to the earth; and if anything warm was in it, it would be carried upward. And the other part of that air, which did not become heavy, would be carried upward along with the exhaled fire. And so, while, of those things which are resolved out of earth and water, something remains in the region of air, and something is carried upward where fire is, one place continues to be filled with air and another filled with fire; but not in such a way that the same air and fire always remain incorrupt in number. What happens is, rather, that, as one portion of air or fire corrupts or is violently expelled toward the earth, another portion is always generated and rises upward from the earth and from the water. In this way, although there is always air in the region of air, and fire in the region of fire, yet there is always a continual turnover as a result of continuous generation and corruption. An analogy of this is seen in a flowing stream, in which there is always water, yet not the same numerical water, but as some flows on, other flows into its place.
Deinde recolligit ea quae dicta sunt, ibi: de eo quidem igitur etc., et dicit: tanta sunt dicta a nobis de eo quod non fiunt nubes, neque inspissatio vaporum in aquam, in superiori parte aeris; et etiam de hoc, quomodo oporteat accipere de loco qui est inter suprema astra et terram, quo scilicet corpore plenus est. 31. Then [31] he summarizes and says: "So much for what we have to say about the fact that in the upper region of air clouds do not form and no thickening of vapors into water takes place; and also about how we must think of the region between the highest star and the earth, i.e., as to what sort of body it is filled with.
Deinde cum dicit: de facta autem caliditate etc., solvit tertiam quaestionem. Et circa hoc duo facit. 32. Then [32] he solves the third question. About this he does two things:
Primo dicit de quo est intentio: dicens quod de caliditate quam sol facit in istis inferioribus, magis conveniret dicere secundum se et diligenter, idest perfecte, in his quae dicenda sunt in libris de sensu: quia calidum est quaedam sensuum passio, est enim obiectum sensus tactus; sensus autem et sensibile habent eandem scientiam, cum adinvicem dicantur quodammodo. Sed quia materia praesens hoc requirit, dicendum est nunc propter quam causam, cum corpora caelestia non sint calida in sui natura, fit ab eis caliditas in istis inferioribus. First, he states his intention and says that, as to the heat produced in these lower bodies by the sun, it would be more suitable to discuss this formally and "diligently," i.e., perfectly, among the matters to be discussed in the books dealing with sense; for "hot is a certain passion of the senses, being the object of the sense of touch. But the sense and the sensible object are treated in the same science, for they are in a certain way referred to each other. However, since the matter at hand demands it, we must now discuss why it is that, though heavenly bodies are not hot as to their nature, yet heat is produced by them in these lower bodies.
Secundo ibi: videmus itaque etc., solvit quaestionem. Et dividitur in duas partes: 33. Secondly [33], he solves the question. And it is divided into two parts:

primo ponit quaestionis solutionem;

secundo probat verum esse quod in quaestione supponebatur, ibi: signum autem sufficiens et cetera.

First, he presents the solution to the question;

Secondly, he proves what he had presupposed in the question, at 37.

Prima dividitur in duas, secundum duas causas quas assignat: secunda incipit ibi: et quia ambiens et cetera. The first is divided into two parts, according to the two causes assigned; The second begins at 36.
Circa primum tria facit. Primo assignat causam propter quam a corporibus caelestibus non calidis existentibus, calor in istis inferioribus generatur. Et dicit quod sensibiliter videmus quod motus, quia potest disgregare aerem et rarefacere, potest etiam eum ignire: nam raritas et igneitas se consequuntur, sicut frigiditas et spissitudo; et propter hoc ea quae feruntur, sicut sagittae, si habeant plumbum et ceram, saepe videntur liquefieri, quasi motu ea calefaciente. Unde nihil inconveniens est, si caelum suo motu calefacit ista inferiora. With respect to the first he does three things. First [33] he assigns the cause on account of which heat is generated in these lower bodies by heavenly bodies not themselves hot. And he says that by sense observation we see that movement, since it can separate and rarefy air, can also inflame it: for rarity and combustion go hand in hand, just as do cooling and thickening; and on this account, things borne along, such as arrows, if they include lead and wax, are often seen to melt, as though motion were making them hot. Hence it is not inconceivable that the heaven, by its motion, should heat these lower bodies.
Secundo ibi: eius quidem igitur etc., assignat causam quare calor in istis inferioribus causatur magis ex motu solis, quam ex motu alicuius alterius corporis superioris. Et dicit quod sol solus sufficiens est facere aestuantem calorem in istis inferioribus: nam calor qui fit ex aliis corporibus caelestibus, est quasi insensibilis respectu caloris qui fit a sole. Huius autem ratio est, quia motus qui causat vehementem calorem, oportet quod sit velox, et quod propinquus nobis. Motus autem astrorum tam fixorum quam quinque errantium quae sunt supra solem, secundum opinionem Aristotelis, scilicet Saturni, Iovis, Martis, Veneris et Mercurii, est quidem velox, remotus tamen a nobis longe; motus autem lunae, licet sit propinquus, est tamen tardus; motus autem solis habet utrumque sufficienter ad causandum calorem in istis inferioribus, scilicet et velocitatem et propinquitatem. 34. Secondly [34], he assigns the cause why heat is caused in these lower bodies more by the motion of the sun than by the motion of some other superior body. And he says that the sun by itself suffices to produce a burning heat in these lower bodies: for the heat produced from other heavenly bodies is almost imperceptible when compared to the heat caused by the sun. The reason for this is that if a motion is to cause vehement heat it must be rapid and close to us. Now the motions, both of the fixed stars, and of the five wandering stars [planets], which are, according to Aristotle, above the sun, namely, Saturn, Jupiter, Mars, Venus and Mercury, are indeed rapid, but they are far from us; on the other hand, the motion of the moon, although it is near, is, however, slow. But the motion of the sun has both, i.e., speed and nearness, in a manner sufficient to cause heat in these lower bodies.
Quod autem hic dicitur de velocitate motus solis, referendum est ad motum quo movetur secundum motum diurnum, non ad proprios motus stellarum. Manifestum est enim quod motum diurnum omnia astra eodem temporis spatio peragunt: quanto autem aliquod caelestium corporum est propinquius centro, tanto minorem circumferentiam circuit, unde tardius movetur. Secundum autem proprios motus, luna velocissime movetur. What is said here about the velocity of the sun's motion is to be referred to its diurnal motion and not to the proper motions of the stars. For it is plain that all the stars complete their diurnal motion during the same period of time: but the closer a heavenly body is to the center, the smaller is the circumference of its orbit and the slower is it moved. But with respect to proper motions, the moon is moved most rapidly.
Tertio ibi: fieri autem magis etc., assignat causam quare magis generatur calor ex motu ipsius solaris corporis, quam ex motu sphaerae eius. Et dicit quod rationabile est quod caliditas fiat magis cum ipso solari corpore. Et huius simile possumus sumere ex his quae sunt apud nos: quia etiam hic, aer vicinus rebus spissis quae feruntur per violentiam, maxime fit calidus. Et hoc accidit etiam rationabiliter: quia maxime motus corporis solidi disgregat aerem; unde cum ipsum corpus solare sit magis solidum quam ceterae partes sphaerae ipsius, cum non sit diaphanum, magis ex motu eius generatur calor, quam ex motu sphaerae eius. Sic igitur propter causam istam caliditas a sole pertingit ad locum istum, quamvis sol non sit calidus. 35. Thirdly [35] he assigns the cause why heat is generated more by the motion of the body of the sun than by the motion of its sphere. And he says that it is reasonable for heat to be produced more by the solar body itself. Something akin to this can be discerned from what happens where we are [on earth]: for here also the air close to thick objects being moved along through violence becomes very hot. And it is reasonable that this should happen: because it is especially the motion of a solid body that dissolves air; hence, since the solar body is more solid than the other parts of its sphere, since it is not diaphanous, heat is generated more from its motion than from the motion of its sphere. This, therefore, explains why heat from the sun reaches this place, even though the sun itself is not hot.
Nec huic causae impedimentum praestat quod luna est inter solem et nos, quae calefieri non potest: quia licet non calefiat a sole, aliquo tamen modo immutatur ab eo, videmus enim quod illuminatur ab eo; non semper autem eadem specie immutationis immutatur medium et extremum, sicut radius solis non inflammat vas vitreum plenum aqua, sed stupam oppositam. Nor is any obstacle to this cause offered by the presence between us and the sun of the moon which cannot become hot; for although it is not heated by the sun, it is nevertheless influenced in a certain manner by the sun, for we observe that it is illuminated by the sun. Yet a medium and an extreme are not always changed with the same species of change: thus a ray of the sun does not ignite a [magnifying] glass filled with water, but the piece of flax placed beyond.
Apparet etiam ratio quare, ubi est umbra, non est tantus calor quantus est in loco ubi radii solares proiiciuntur: quia scilicet umbra causatur ex aliquo corpore opposito soli, quod interrumpit continuationem transmutationis quae est a sole; sed actio solis pertingit ad locum umbrae per quandam reflexionem. Also the reason is apparent why, where a shadow is, there is not as much heat as in a place where the sun's rays strike: it is because a shadow is caused by a body blocking the sun and interrupting the continuing transmutation deriving from the sun; however, the action of the sun does reach the place where a shadow is by a sort of reflexion.
Nec tamen putandum est quod motus solis, inquantum est motus tantum, causet calorem: sed inquantum est motus talis corporis, in sua natura habentis virtutem calefaciendi. Omnes enim formae corporum inferiorum reducuntur in corpora caelestia sicut in quaedam principia: et inde est quod diversa corpora caelestia diversos effectus in rebus corporalibus habent, non solum secundum calidum, sed etiam secundum alias passiones et formas. Nor should it be supposed that the sun's motion, as motion only, causes heat; rather, it is in so far as it is the motion of such a body, i.e., of a body having in its nature the power to cause heat. For all the forms of the lower bodies are reduced back to the heavenly bodies as to certain principles: that is why diverse heavenly bodies produce diverse effects in bodily things, not only so far as heat is considered, but as far as other passions and forms are concerned.
Deinde cum dicit: et quia ambiens etc., ponit propriam causam caliditatis generatae ex motu solis: quae tamen non est universalis, sed particularis. Unde dicit quod frequenter ignis qui ambit inferiores partes mundi, ex motu corporis caelestis, fertur quadam violentiam deorsum, et spargitur per aerem: quia, sicut supra dictum est, superior pars aeris et ignis quendam fluxum habet ex motu caeli. 36. Then [36] he presents a proper cause of heat generated from the motion of the sun: yet not the universal cause but a particular cause. Hence he says that the fire which surrounds the lower parts of the world as a result of a heavenly body's motion is often violently thrust downwards and scattered through the air: because, as was said above, the upper part of the air and fire have a flow on account of the motion of the heaven.
Deinde cum dicit: signum autem sufficiens etc., manifestat quod quaestio supponebat, scilicet quod corpora caelestia non sunt calida aut ignita: et hoc per duo signa. Primum est quia ibi non apparent discursus astrorum quae videntur cadentia, quae ex ignitione generantur in inferiori loco: quod non esset si corpora caelestia essent calida aut ignita; quia ubi est motus maior et velocior, ibi citius aliquid ignitur. 37. Then [37] he shows something which the question supposed, namely, that heavenly-bodies are not hot or fiery; this he does by two signs. The first is that in that region we do not see the paths of those stars which seem to be falling [i.e., shooting stars], which are generated by combustion in the lower regions. This would not be the case if heavenly bodies were hot and fiery, because, wherever there is a greater and speedier motion, there something is ignited more readily.
Secundum signum est quod sol, qui maxime videtur esse calidus ex effectu, videtur coloris albi et non ignei. The second sign is that the sun, which especially seems to be hot, considering its effects, is seen to be of a white, and not a fiery, color.

Lecture 6
Shooting stars and meteors — their cause and difference
Chapter 4
(341b.) τούτων δὲ διωρισμένων, λέγωμεν διὰ τίν' αἰτίαν αἵ τε φλόγες αἱ καιόμεναι φαίνονται περὶ τὸν οὐρανὸν καὶ οἱ διαθέοντες ἀστέρες καὶ οἱ καλούμενοι ὑπό τινων δαλοὶ καὶ αἶγες ταῦτα γὰρ πάντ' ἐστὶν τὸ αὐτὸ καὶ διὰ τὴν αὐτὴν αἰτίαν, διαφέρει δὲ τῷ μᾶλλον καὶ ἧττον. 38 Having determined these principles let us explain the cause of the appearance in the sky of burning flames and of shooting-stars, and of 'torches', and 'goats', as some people call them. All these phenomena are one and the same thing, and are due to the same cause, the difference between them being one of degree.
ἀρχὴ δέ ἐστιν καὶ τούτων καὶ πολλῶν ἄλλων ἥδε. θερμαινομένης γὰρ τῆς γῆς ὑπὸ τοῦ ἡλίου τὴν ἀναθυμίασιν ἀναγκαῖον γίγνεσθαι μὴ ἁπλῆν, ὥς τινες οἴονται, ἀλλὰ διπλῆν, τὴν μὲν ἀτμιδωδεστέραν τὴν δὲ πνευματωδεστέραν, τὴν μὲν τοῦ ἐν τῇ γῇ καὶ ἐπὶ τῇ γῇ ὑγροῦ ἀτμίδα, τὴν δ' αὐτῆς τῆς γῆς οὔσης ξηρᾶς καπνώδη καὶ τούτων τὴν μὲν πνευματώδη ἐπιπολάζειν διὰ τὸ θερμόν, τὴν δὲ ὑγροτέραν ὑφίστασθαι διὰ τὸ βάρος. καὶ διὰ ταῦτα τοῦτον τὸν τρόπον κεκόσμηται τὸ πέριξ πρῶτον μὲν γὰρ ὑπὸ τὴν ἐγκύκλιον φοράν ἐστιν τὸ θερμὸν καὶ ξηρόν, ὃ λέγομεν πῦρ (ἀνώνυμον γὰρ τὸ κοινὸν ἐπὶ πάσης τῆς καπνώδους διακρίσεως ὅμως δὲ διὰ τὸ μάλιστα πεφυκέναι τὸ τοιοῦτον ἐκκαίεσθαι τῶν σωμάτων οὕτως ἀναγκαῖον χρῆσθαι τοῖς ὀνόμασιν), ὑπὸ δὲ ταύτην τὴν φύσιν ἀήρ. 39 The explanation of these and many other phenomena is this. When the sun warms the earth the evaporation which takes place is necessarily of two kinds, not of one only as some think. One kind is rather of the nature of vapour, the other of the nature of a windy exhalation. That which rises from the moisture contained in the earth and on its surface is vapour, while that rising from the earth itself, which is dry, is like smoke. Of these the windy exhalation, being warm, rises above the moister vapour, which is heavy and sinks below the other. Hence the world surrounding the earth is ordered as follows. First below the circular motion comes the warm and dry element, which we call fire, for there is no word fully adequate to every state of the fumid evaporation: but we must use this terminology since this element is the most inflammable of all bodies. Below this comes air.
δεῖ δὴ νοῆσαι οἷον ὑπέκκαυμα τοῦτο ὃ νῦν εἴπομεν πῦρ περιτετάσθαι τῆς περὶ τὴν γῆν σφαίρας ἔσχατον, ὥστε μικρᾶς κινήσεως τυχὸν ἐκκαίεσθαι πολλάκις ὥσπερ τὸν καπνόν ἔστι γὰρ ἡ φλὸξ πνεύματος ξηροῦ ζέσις. 40 We must think of what we just called fire as being spread round the terrestrial sphere on the outside like a kind of fuel, so that a little motion often makes it burst into flame just as smoke does: for flame is the ebullition of a dry exhalation.
ᾗ ἂν οὖν μάλιστα εὐκαίρως ἔχῃ ἡ τοιαύτη σύστασις, ὅταν ὑπὸ τῆς περιφορᾶς κινηθῇ πως, ἐκκάεται. διαφέρει δ' ἤδη κατὰ τὴν τοῦ ὑπεκκαύματος θέσιν ἢ τὸ πλῆθος 41 So whenever the circular motion stirs this stuff up in any way, it catches fire at the point at which it is most inflammable. The result differs according to the disposition and quantity of the combustible material.
ἂν μὲν γὰρ πλάτος ἔχῃ καὶ μῆκος τὸ ὑπέκκαυμα, πολλάκις ὁρᾶται καιομένη φλὸξ ὥσπερ ἐν ἀρούρᾳ καιομένης καλάμης, ἐὰν δὲ κατὰ μῆκος μόνον, οἱ καλούμενοι δαλοὶ καὶ αἶγες καὶ ἀστέρες. ἐὰν μὲν πλέον τὸ ὑπέκκαυμα ᾖ κατὰ τὸ μῆκος ἢ τὸ πλάτος, ὅταν μὲν οἷον ἀποσπινθηρίζῃ ἅμα καιόμενον (τοῦτο δὲ γίγνεται διὰ τὸ παρεκπυροῦσθαι, κατὰ μικρὰ μέν, ἐπ' ἀρχὴν δέ), αἲξ καλεῖται, ὅταν δ' ἄνευ τούτου τοῦ πάθους, δαλός. ἐὰν δὲ τὰ μήκη τῆς ἀναθυμιάσεως κατὰ μικρά τε καὶ πολλαχῇ διεσπαρμένα ᾖ καὶ ὁμοίως κατὰ πλάτος καὶ βάθος, οἱ δοκοῦντες ἀστέρες διάττειν γίγνονται. ὁτὲ μὲν οὖν ὑπὸ τῆς κινήσεως ἡ ἀναθυμίασις ἐκκαιομένη γεννᾷ αὐτά ὁτὲ δὲ ὑπὸ τοῦ διὰ τὴν ψύξιν (342a.) συνισταμένου ἀέρος ἐκθλίβεται καὶ ἐκκρίνεται τὸ θερμόν, διὸ καὶ ἔοικεν ἡ φορὰ ῥίψει μᾶλλον αὐτῶν, ἀλλ' οὐκ ἐκκαύσει. 42 If this is broad and long, we often see a flame burning as in a field of stubble: if it burns lengthwise only, we see what are called 'torches' and 'goats' and shooting-stars. Now when the inflammable material is longer than it is broad sometimes it seems to throw off sparks as it burns. (This happens because matter catches fire at the sides in small portions but continuously with the main body.) Then it is called a 'goat'. When this does not happen it is a 'torch'. But if the whole length of the exhalation is scattered in small parts and in many directions and in breadth and depth alike, we get what are called shooting-stars. The cause of these shooting-stars is sometimes the motion which ignites the exhalation. At other times the air is condensed by cold and squeezes out and ejects the hot element; making their motion look more like that of a thing thrown than like a running fire.
Positis his quae ad manifestationem sequentium philosophus induxerat, incipit 38. Having laid down those things introduced to explain what is to follow, the Philosopher begins:

primo determinare de his quae in alto ex materia sicca generantur;

secundo de his quae generantur ex materia humida in alto, ibi: de loco autem positione et cetera.

First, to determine concerning things generated on high out of dry matter;

Secondly, things generated on high from moist matter (L. 14).

Prima dividitur in tres: The first is divided into three parts:

primo determinat de stellis cadentibus, et his quae similem habent causam;

secundo determinat de cometis, ibi: de cometis autem etc.;

tertio de lacteo circulo, qui dicitur Galaxia, ibi: qualiter autem et propter quam causam et cetera.

In the first he determines about falling stars and things having a like cause;

In the second about comets (L. 9);

In the third about the milky circle called the "galaxy" (L. 12).

Circa primum duo facit: About the first he does two things:

primo enim determinat de stellis cadentibus et aliis huiusmodi;

secundo determinat de quibusdam aliis apparitionibus quae in aere videntur, ibi: apparent autem aliquando nocte et cetera.

First, he determines about falling stars and other similar things;

Secondly, about certain other apparitions seen in the air (L. 8).

Circa primum duo facit. About the first he does two things:
Primo dicit de quo est intentio. Et dicit quod post determinationem praedictorum, dicendum est propter quam causam apparent in caelo flammae accensae, et sidera discurrentia, et vocati a quibusdam dali, idest titiones, et aeges, idest caprae. Ideo autem dicendum est simul de omnibus istis, quia omnia huiusmodi sunt idem secundum speciem, et secundum eandem causam fiunt; sed differunt per magis et minus, ut infra patebit. First, he states his intention [38] and says that, having determined the foregoing, we must explain the cause of the appearance in the heaven of burning flames and of shooting stars and of so-called dali, i.e., torches, and aeges, i.e., goats. They will be discussed at one and the same time, because they are all alike in kind and produced by the same cause, and differ only in degree, as will be clear below.
Secundo ibi: principium autem et horum etc., determinat propositum. Et circa hoc duo facit. 39. Secondly [39], he determines his proposition, about which he does two things:
Primo praemittit causas generationis praedictorum. Et dicit quod principium praedictarum passionum et multarum aliarum, tam activum quam materiale, est quod dicetur. Cum enim terra calefacta fuerit per motum solis, oportet aliquam exhalationem resolvi a terra. Quae non est uniusmodi, ut quidam putant, sed est duplex: quaedam enim est magis vaporosa et humida, quaedam vero est magis spumosa et sicca: nam ab humido aqueo quod est super terram, resolvitur et elevatur vaporosa exhalatio et humida; ab ipsa autem terra, quae est siccae naturae, elevatur exhalatio fumosa sive spumosa. Harum autem exhalationum, spumosa quidem supereminet propter calidum, quod in ea dominatur et magis ipsam subtiliat: siccum enim et calidum leve est, et talis est ignis natura. Vaporosa autem exhalatio, quae est magis humida, subest spumosae propter pondus, non enim ita rarefit: calidum enim et humidum pertinent ad naturam aeris, qui subest igni calido et sicco existenti. First, he states the causes generating the aforesaid, and says that the principle, both active and passive, of the aforesaid phenomena and of many others is what he will indicate. For when the earth has been warmed by the sun's motion, a certain exhalation is necessarily released from the earth. This is not of one sort, as some think, but is twofold: one is more vaporous and moist, the other more foam-like and dry — for from the aqueous moisture upon the earth's surface there is released and lifted on high a vaporous exhalation which is moist; from the earth itself, which is by nature dry, there is raised a fume-like or foam-like exhalation. Of these, the foam-like exhalation rises above the other on account of warmth which dominates in it and renders it more subtle: for the dry and warm is light — and fire is of this nature. But the vaporous exhalation, which is more moist, finds its place under the foam-like, being heavier, for it is not so fine: hot and moist pertain to the nature of the air, which is below fire, which is hot and dry.
Et huic attestatur ordo elementorum quae sunt circa terram. Nam sub circulari motu caeli primo est locatum id quod est calidum et siccum, quod communiter dicitur ignis, licet non sit nomen proprium, ut supra dictum est: quia enim id quod est commune omni fumosae exhalationi, est innominatum, et quod tale est maxime natum est exuri, propter hoc sic necessarium fuit uti nominibus, ut talis fumosa exhalatio ignis diceretur. Sub fumosa autem exhalatione est aer. Sic ergo posita est causa et effectiva praedictarum passionum, quae est latio solis, et causa materialis, quae est fumosa exhalatio. The very order of the elements surrounding the earth attests to this. For under the circular motion of the heaven there is first located what is hot and dry and which is commonly called "fire," though that is not its proper name, as has been said above: for, since the item common to every smoky exhalation has no name, and such is especially apt to burn, consequently, it was necessary to use words in keeping, and so such a fume-like evaporation comes to be called "fire." Under this fume-like exhalation is air. Thus we have posited both the effective cause of the aforesaid passions, which is the sun's movement, and the material cause, namely, the fume-like exhalation.
Secundo ibi: oportet autem intelligere etc., determinat de generatione praedictarum passionum. Et circa hoc duo facit: 40. Secondly [40], he determines concerning the generation of the aforesaid passions. About this he does two things:

primo assignat rationem generationis harum passionum;

secundo assignat rationem quorundam accidentium circa ipsas, ibi: propter positionem et cetera.

First, he assigns the cause of their generation;

Secondly, the reason why certain things accompany them, at 47.

Circa primum tria facit: About the first he does three things:

primo assignat causam praedictarum passionum in communi;

secundo assignat differentiam earum adinvicem, ibi: quacumque igitur se habeat maxime etc.;

tertio movet dubitationem circa determinata, ibi: dubitabit utique quis et cetera.

First, he gives the cause of the aforesaid passions in common;

Secondly, their mutual differences, at 41;

Thirdly, he raises a question concerning what he has determined (L. 7).

Dicit ergo primo quod, secundum praedicta, oportet intelligere hoc quod nunc diximus ignem, scilicet fumosam exhalationem, esse ut quoddam hyppeccauma, idest quandam materiam incendii; et quod ordinatur in rotunditate quae est circa terram ultimo (incipiendo scilicet a terra); ita quod propter propinquitatem ad motum caelestem, saepe exuratur, sortiens augmentum caloris, modico motu, idest cum parum movetur ex motu superioris corporis; sicut accidit de fumo, dum incenditur et fit flamma: nihil enim est aliud flamma quam ardor spiritus, idest fumi, sicci. Ipsa ergo flammatio praedicti hypeccaumatis, communiter loquendo, est generatio praedictarum passionum, ex appropinquatione materiae praeparatae causae efficienti. He says therefore first [40] that, in the light of the foregoing, we must understand what we have just now called "fire" to be as a certain "fuel," i.e., a combustible material, and that it is situated in the sphericity which is about the earth in the last place (beginning, that is, from the earth), Hence, on account of its proximity to the heavenly motion it often bursts into flame, being heated when only "slightly moved," i.e., when slightly stirred by the motion of the body above it, as happens in the case of smoke, when it is ignited and becomes flame: for a flame is nothing but the burning of a dry "spirit," i.e., smoke. Therefore the ignition of the above-mentioned fuel, commonly speaking, is responsible for the generation of the aforesaid passions, when matter which is prepared is placed in the proximity of the efficient cause.
Deinde cum dicit: quacumque igitur se habeat maxime etc., assignat differentiam praedictarum passionum. Et circa hoc duo facit. 41. Then [41] he explains the differences among the aforesaid passions. About this he does two things:
Primo ostendit unde sit accipienda differentia. Et dicit quod ex qua parte se habet praedicta materia (quocumque modo se habeat talis consistentia, idest praedicta materia incendii) optime disposita ad hoc quod igniatur, tali modo exuritur, quando fuerit mota per calefactionem a circulari motu caeli: et differt passio exignita secundum positionem praedictae materiae et multitudinem. First he shows what is the basis for the difference. And he says that from whatever source the aforesaid matter is had (regardless of how this "consistency" is obtained, namely, the aforesaid matter for burning), and when it is most perfectly disposed to be ignited, then it is so ignited in such a way by heating from the circular motion of the heaven: and the ignited passion varies according to the position and amount of the aforesaid matter.
Secundo ibi: si quidem enim etc., assignat differentiam praedictarum passionum. Et dicit quod si praedicta materia habeat magnam latitudinem et longitudinem, videtur esse quaedam flamma accensa in caelo, sicut cum stipula ardet in area. Si vero non habeat multum in latitudine, sed solum in longitudine, generantur et apparent illic dali, idest titiones, et aeges, idest caprae, et sidera discurrentia. Quia si praedicta materia fuerit plus secundum longitudinem quam latitudinem, et quando simul dum comburitur, ignis scintillat, idest videtur salire et discurrere quasi aeges, idest sicut caprae (quod quidem fit propter hoc quod incipit igniri non tota materia simul, sed secundum aliquas parvas partes, incipiens ex aliquo principio illius materiae): quando inquam hoc fit, tunc vocatur aeges, idest capra. Sed quando fit incensio praedictae materiae sine praedicta passione, idest sine scintillatione, eo quod materia tota accenditur simul, tunc vocatur dalus, idest titio. 42. Secondly [42], he determines the differences among the aforesaid passions. And he says that if the aforesaid matter has great width and length, there appears to be a certain flame enkindled in the heaven, similar to stubble burning in a field [area]. But if it does not have great width, but only length, then "dali," i.e., torches, and "aeges," i.e., goats, and shooting stars are generated and appear there. For if the aforesaid matter is more in length than in width, and when it burns, the fire "scintillates," i.e., seems to leap and run about like "aeges," i.e., goats (which happens because not all the matter begins to be ignited at once but according to certain small sections, beginning from some starting-point in the matter), when, I say, this happens, it is called "aeges," i.e., a goat. But when the burning of the aforesaid matter takes place without the aforesaid passion, i.e., without scintillation, because the entire material is ignited at once, then it is called a "dalus," i.e., a torch.
Sed quando exhalatio non fuerit continua, sed frequens et dispersa per modicas partes et multis modis, tam secundum longitudinem quam secundum latitudinem, quam etiam secundum profunditatem, tunc fiunt sidera quae putantur volare: eo quod illa materia cito consumitur, et desinit esse ibi ubi prius accensa fuerat, sicut accidit de stuppa, si modicum de ea per longitudinem disponatur et accendatur: currit enim combustio, et videtur similis esse motui alicuius corporis ignei. However, when the exhalation is not continuous, but frequent, and scattered in small areas, and in many ways, both according to length and according to width and even depth, then appear stars that seem to fly, because the material is rapidly consumed and ceased to be where it was previously burning, as happens with flax, if a small amount of it is laid down lengthwise and ignited: for the combustion seems to run along and seems similar to the movement of some fiery body.
Sic igitur patet quod plurimum habet de materia flamma accensa; mediocriter (propter quod vocantur) titiones et caprae; minimum autem stellae discurrentes, et propter hoc frequentius apparent. In this way, it is therefore plain that the burning flame has most material; a medium amount what are called "torches" and "goats," and least for shooting stars, which accounts for their rather frequent occurrence.
Sed quia sidera volantia habent aliam causam suae generationis, ideo subiungit quod aliquando exhalatio exusta a motu solis generat ea; aliquando autem, inspissato aere propter frigus, illud quod est ibi calidum, inspissatum extruditur inferius et separatur a frigido; et propter hoc illud inspissatum ignitur, et videtur stella cadens. Propter quod et motus siderum sic cadentium non assimilatur exustioni, sed magis proiectioni. 43, But because shooting stars have an additional cause of their generation, he adds that sometimes an exhalation ignited by the sun's movement generates them, but sometimes, too, when cold causes air to thicken, that which is hot within, being thickened, is forced out downward and is separated from the cold; this causes the thickened mass to ignite and a falling star is seen. That is also why the motion of stars falling in that way is not assimilated to a burning, but rather to a projecting.

Lecture 7
Solution of problems concerning shooting stars
Chapter 4 cont.
ἀπορήσειε γὰρ ἄν τις πότερον ὥσπερ ἡ ὑπὸ τοὺς λύχνους τιθεμένη ἀναθυμίασις ἀπὸ τῆς ἄνωθεν φλογὸς ἅπτει τὸν κάτωθεν λύχνον (θαυμαστὴ γὰρ καὶ τούτου ἡ ταχυτής ἐστιν καὶ ὁμοία ῥίψει, ἀλλ' οὐχ ὡς ἄλλου καὶ ἄλλου γιγνομένου πυρός), ἢ ῥίψεις τοῦ αὐτοῦ τινος σώματός εἰσιν αἱ διαδρομαί. 43 For the question might be raised whether the 'shooting' of a 'star' is the same thing as when you put an exhalation below a lamp and it lights the lower lamp from the flame above. For here too the flame passes wonderfully quickly and looks like a thing thrown, and not as if one thing after another caught fire. Or is a 'star' when it 'shoots' a single body that is thrown?
ἔοικε δὴ δι' ἄμφω καὶ γὰρ οὕτως ὡς ἡ ἀπὸ τοῦ λύχνου γίγνεται, καὶ ἔνια διὰ τὸ ἐκθλίβεσθαι ῥιπτεῖται, ὥσπερ οἱ ἐκ τῶν δακτύλων πυρῆνες, ὥστε καὶ εἰς τὴν γῆν καὶ εἰς τὴν θάλατταν φαίνεσθαι πίπτοντα, καὶ νύκτωρ καὶ μεθ' ἡμέραν καὶ αἰθρίας οὔσης. κάτω δὲ ῥιπτεῖται διὰ τὸ τὴν πύκνωσιν εἰς τὸ κάτω ῥέπειν τὴν ἀπωθοῦσαν. διὸ καὶ οἱ κεραυνοὶ κάτω πίπτουσιν, <τοῦ πυρὸς ἄνω φερομένου κατὰ φύσιν> πάντων γὰρ τούτων ἡ γένεσις οὐκ ἔκκαυσις ἀλλ' ἔκκρισις ὑπὸ τῆς ἐκθλίψεώς ἐστιν, ἐπεὶ κατὰ φύσιν γε τὸ θερμὸν ἄνω πέφυκε φέρεσθαι πᾶν. 44 Apparently both cases occur: sometimes it is like the flame from the lamp and sometimes bodies are projected by being squeezed out (like fruit stones from one's fingers) and so are seen to fall into the sea and on the dry land, both by night and by day when the sky is clear. They are thrown downwards because the condensation which propels them inclines downwards. Thunderbolts fall downwards for the same reason: their origin is never combustion but ejection under pressure, since naturally all heat tends upwards.
ὅσα μὲν οὖν μᾶλλον ἐν τῷ ἀνωτάτω τόπῳ συνίσταται, ἐκκαιομένης γίγνεται τῆς ἀναθυμιάσεως, ὅσα δὲ κατώτερον, ἐκκρινομένης διὰ τὸ συνιέναι καὶ ψύχεσθαι τὴν ὑγροτέραν ἀναθυμίασιν αὕτη γὰρ συνιοῦσα καὶ κάτω ῥέπουσα ἀπωθεῖ πυκνουμένη καὶ κάτω ποιεῖ τοῦ θερμοῦ τὴν ῥῖψιν 45 When the phenomenon is formed in the upper region it is due to the combustion of the exhalation. When it takes place at a lower level it is due to the ejection of the exhalation by the condensing and cooling of the moister evaporation: for this latter as it condenses and inclines downward contracts, and thrusts out the hot element and causes it to be thrown downwards.
διὰ δὲ τὴν θέσιν τῆς ἀναθυμιάσεως, ὅπως ἂν τύχῃ κειμένη τοῦ πλάτους καὶ τοῦ βάθους, οὕτω φέρεται ἢ ἄνω ἢ κάτω ἢ εἰς τὸ πλάγιον. τὰ πλεῖστα δ' εἰς τὸ πλάγιον διὰ τὸ δύο φέρεσθαι φοράς, βίᾳ μὲν κάτω, φύσει δ' ἄνω πάντα γὰρ κατὰ τὴν διάμετρον φέρεται τὰ τοιαῦτα. διὸ καὶ τῶν διαθεόντων ἀστέρων ἡ πλείστη λοξὴ γίγνεται φορά. πάντων δὴ τούτων αἴτιον ὡς μὲν ὕλη ἡ ἀναθυμίασις, ὡς δὲ τὸ κινοῦν ὁτὲ μὲν ἡ ἄνω φορά, ὁτὲ δ' ἡ τοῦ ἀέρος συγκρινομένου πῆξις. 46 The motion is upwards or downwards or sideways according to the way in which the evaporation lies, and its disposition in respect of breadth and depth. In most cases the direction is sideways because two motions are involved, a compulsory motion downwards and a natural motion upwards, and under these circumstances an object always moves obliquely. Hence the motion of 'shooting-stars' is generally oblique. So the material cause of all these phenomena is the exhalation, the efficient cause sometimes the upper motion, sometimes the contraction and condensation of the air.
πάντα δὲ κάτω ταῦτα σελήνης γίγνεται. σημεῖον δ' ἡ φαινομένη αὐτῶν ταχυτὴς ὁμοία οὖσα τοῖς ὑφ' ἡμῶν ῥιπτουμένοις, ἃ διὰ τὸ πλησίον εἶναι ἡμῶν πολὺ δοκεῖ τῷ τάχει παραλλάττειν ἄστρα τε καὶ ἥλιον καὶ σελήνην. 47 Further, all these things happen below the moon. This is shown by their apparent speed, which is equal to that of things thrown by us; for it is because they are close to us, that these latter seem far to exceed in speed the stars, the sun, and the moon.
Quia assignavit duas causas generationis siderum discurrentium, hic movet quandam dubitationem circa ea. Et circa hoc duo facit. 44. Because he assigned two causes for the generation of shooting stars, he now raises a certain problem about them. With respect to this he does two things:
Primo movet dubitationem: quae est utrum discursus siderum currentium fiat hoc modo, sicut cum fumosa exhalatio inferioris candelae incenditur a flamma superioris candelae vel lucernae (tunc enim videtur ignis descendere cum mirabili velocitate, et videtur proiectio unius et eiusdem ignis, et non videtur quod ignis fiat in alio et alio corpore); aut secundum veritatem discursus siderum cadentium sunt proiectiones alicuius eiusdem corporis cadentis. First, he raises the problem [43] which is this: whether the trajectory of shooting stars is the same as when the smoke-like exhalation of a lower candle is set afire by the flame of a higher candle or light (for in such a case the fire is seen to travel downward with marvelous speed and there appears to be the projection of one and the same fire instead of fire igniting in two distinct bodies); or whether the truth is that the trajectories of falling-stars are the projections of some same falling body.
Secundo ibi: videtur itaque etc., solvit propositam dubitationem. Et circa hoc duo facit. 45. Secondly [45], he solves this problem. Concerning it he does two things:
Primo dicit quod propter utramque causam videtur esse discursus siderum cadentium. Quandoque enim sic fit talis discursus per continuam ignitionem materiae, sicut dictum est de fumo lucernarum: quandoque autem aliqua ignita proiiciuntur, propter hoc quod expelluntur a superiori frigore, sicut cum aliqua cadunt expulsa ex digitis, ut nux cerasii. Unde et in terram et in mare videntur cadentia, et hoc tam in die quam in nocte, serenitate existente. Dicit autem de die, et non solum per noctem, quia huiusmodi ignis cadens, nisi appropinquaret terrae per motum, non appareret de die. Dicit autem serenitate existente, quia tempore nebuloso talis ignis ab humiditate nubium et aeris extingueretur. First, he says that the trajectories of falling stars seem to be due to both causes. For sometimes such a trajectory results from the continuous enkindling of matter, as was said of the smoke from lamps; but sometimes certain ignited substances are projected out as the result of being expelled by a higher coldness, much like a cherry pit squeezed out by one's fingers. Hence they are seen falling into the earth and sea, during the day as well as the night, when the sky is clear. He says, "during the day" and not at night only, because unless such a falling fire approached the earth through movement, it would not be visible during the day. Likewise he says, "when the sky is clear," because when is is cloudy, such fire would be snuffed out by the humidity of the clouds and air.
Sed licet ista quae cadunt expulsa sint ignita, et ita, ut videtur, deberent esse levia et ascendere, tamen deorsum iaciuntur, quia coagulatio frigoris impellens ea inclinat deorsum. Et propter hanc causam fulmina cadunt deorsum, licet sint ignita: quia generatio omnium horum sic cadentium non est per exustionem ab aliquo calido igniente, sed per separationem ab aliquo frigido expellente; quia omne calidum secundum naturam habet ferri sursum. But although those things expelled are on fire, and should, it would seem, on that account have to be light and therefore ascend, they are nevertheless cast downwards, because the condensation of cold driving them inclines them downwards. This is the reason why thunderbolts fall downwards even though ignited: for the generation of all things falling in this way is due, not to their being set afire by something hot which ignites them, but to their being detached by something cold which expels them — since by nature everything hot is borne aloft.
Secundo ibi: quaecumque quidem igitur etc., assignat differentiam inter discursus siderum ex duabus causis provenientes. Et dicit quod quaecumque siderum discurrentium magis generantur in supremo loco, fiunt per adustionem exhalationis: quaecumque vero demissius generantur, fiunt propter hoc quod humidior exhalatio concernitur, idest inspissatur, et infrigidatur. Haec enim humida exhalatio congregata deorsum tendens, impellit et quasi proiicit calidum deorsum, cum aliqua materia inspissata. 46. Secondly [45], he explains the difference between the trajectories of the stars arising from these two causes. And he says that whatever shooting stars are generated more in the highest region, these are caused by the combustion of an exhalation; but the ones generated farther down are caused by the moister exhalation "mixing together," i.e., condensing and cooling. For this moist exhalation, now concentrated and inclining downwards, pushes and, as it were, thrusts downward the hot element, together with some condensed matter.
Deinde cum dicit: propter positionem etc., assignat rationem quorundam accidentium circa praedicta. Et circa hoc duo facit: 47. Then [46] he explains certain phenomena accompanying these events. About this he does two things:

primo assignat rationem de modo motus huiusmodi astrorum cadentium, secundum dispositionem ipsorum;

secundo determinat locum generationis eorum, ibi: omnia autem haec sub luna et cetera.

First, he explains the reason for the type of motion of such falling stars;

Secondly, he determines the place where they are generated, at 48.

Dicit ergo primo quod secundum diversam positionem exhalationis in latitudine et profunditate, secundum hoc diversimode fertur stella cadens, aut sursum aut deorsum aut ad latus expulsionis a frigore. Quia si materia frigida inspissata expellens fuerit adunata sursum, stella cadens per expulsionem fertur deorsum; si autem fuerit adunata inferius, fertur sursum; cum autem ex neutra parte adunatur, tunc fertur ad latus, quasi oblique et in diametrum. Et hoc pluries evenit: quia calidum expulsum fertur duabus lationibus; naturaliter enim, inquantum est calidum, fertur sursum, sed per violentiam expulsionis fertur deorsum; omnia autem talia, quorum motus sic compositi sunt, feruntur secundum diametrum, idest oblique, quia talis motus est quasi medius inter ascensum et descensum. Et ideo motus discurrentium siderum ut plurimum fit obliquus. He says therefore first that, depending on the different position of the exhalation with respect to the sides or depth [i.e., top or bottom], the falling star will be moved differently — either above or below, or to the side, of its point of ejection by the cold. For if the condensed cold matter which does the ejecting has come together above, the falling star is moved downward by the expulsion; but if the matter has collected below, then it is moved upward; if it comes together in neither place, then its [the star's] motion is sideways, as though obliquely or along the diameter. And this often happens: for the ejected hot mass is moved with two motions: by nature, as hot, it is moved upwards; but through the violence of the ejection, it is moved downwards. But all such things, whose motions are so combined, are moved "according to the diameter," i.e., obliquely, since such a motion is as though a mean between ascent and descent. As a result the motion of falling stars is most often oblique.
His autem dictis, epilogat quae dicta sunt. Et dicit quod omnium praedictorum causa materialis est exhalatio: causa autem movens est duplex; quandoque quidem motus superioris corporis, quandoque autem condensatio aeris inspissati ex frigore, et ex hoc expellentis calidum. Then he summarizes what has been set forth and says that the material cause of all the foregoing is an exhalation; but the movent cause is twofold: for sometimes it is the movement of a higher body, sometimes it is the condensing of air thickened by coldness, and subsequently forcing out the hot.
Deinde cum dicit: omnia autem haec sub luna etc., determinat locum generationis praedictorum. Et dicit quod omnia praedicta generantur sub luna. Cuius signum est quod apparent nobis valde velociter moveri, sicut illa quae proiiciuntur a nobis, utpote sagittae et alia huiusmodi, quae propter propinquitatem ad nos videntur excedere velocitatem astrorum et solis et lunae; quamvis manifestum sit quod, secundum rei veritatem, superiora corpora multo velocius moventur quam aliquid quod sit hic. 48. Then [47] he determines the place where the aforesaid are produced and says that they are all produced below the moon. A sign of this is that they appear to us to be moving very rapidly, as do things we project, such as arrows and the like, which, for being close to us, seem to be travelling faster than the stars and sun and moon — although it is plain that, in truth, the higher bodies are moved much faster than anything here.

Lecture 8
Cause of other phenomena appearing at night, and of certain that do not
Chapter 8
φαίνεται δέ ποτε συνιστάμενα νύκτωρ αἰθρίας οὔσης πολλὰ φάσματα ἐν τῷ οὐρανῷ, οἷον χάσματά τε καὶ βόθυνοι καὶ αἱματώδη χρώματα. 48 Sometimes on a fine night we see a variety of appearances that form in the sky: 'chasms' for instance and 'trenches' and blood-red colours.
αἴτιον δὲ ἐπὶ τούτων τὸ (342b.) αὐτό ἐπεὶ γὰρ φανερός ἐστι συνιστάμενος ὁ ἄνω ἀὴρ ὥστ' ἐκπυροῦσθαι, καὶ τὴν ἐκπύρωσιν ὁτὲ μὲν τοιαύτην γίγνεσθαι ὥστε φλόγα δοκεῖν καίεσθαι, ὁτὲ δὲ οἷον δαλοὺς φέρεσθαι καὶ ἀστέρας, οὐδὲν ἄτοπον εἰ χρωματίζεται ὁ αὐτὸς οὗτος ἀὴρ συνιστάμενος παντοδαπὰς χρόας διά τε γὰρ πυκνοτέρου διαφαινόμενον ἔλαττον φῶς καὶ ἀνάκλασιν δεχόμενος ὁ ἀὴρ παντοδαπὰ χρώματα ποιήσει, μάλιστα δὲ φοινικοῦν ἢ πορφυροῦν, διὰ τὸ ταῦτα μάλιστα ἐκ τοῦ πυρώδους καὶ λευκοῦ φαίνεσθαι μειγνυμένων κατὰ τὰς ἐπιπροσθήσεις, οἷον ἀνίσχοντα τὰ ἄστρα καὶ δυόμενα, ἐὰν ᾖ καῦμα, καὶ διὰ καπνοῦ φοινικᾶ φαίνεται. καὶ τῇ ἀνακλάσει δὲ ποιήσει, ὅταν τὸ ἔνοπτρον ᾖ τοιοῦτον ὥστε μὴ τὸ σχῆμα ἀλλὰ τὸ χρῶμα δέχεσθαι. τοῦ δὲ μὴ πολὺν χρόνον μένειν ταῦτα ἡ σύστασις αἰτία ταχεῖα οὖσα. 49 These, too, have the same cause. For we have seen that the upper air condenses into an inflammable condition and that the combustion sometimes takes on the appearance of a burning flame, sometimes that of moving torches and stars. So it is not surprising that this same air when condensing should assume a variety of colours. For a weak light shining through a dense air, and the air when it acts as a mirror, will cause all kinds of colours to appear, but especially crimson and purple. For these colours generally appear when fire-colour and white are combined by superposition. Thus on a hot day, or through a smoky, medium, the stars when they rise and set look crimson. The light will also create colours by reflection when the mirror is such as to reflect colour only and not shape. These appearances do not persist long, because the condensation of the air is transient.
τὰ δὲ χάσματα ἀναρρηγνυμένου τοῦ φωτὸς ἐκ κυανοῦ καὶ μέλανος ποιεῖ τι βάθος ἔχειν δοκεῖν. πολλάκις δ' ἐκ τῶν τοιούτων καὶ δαλοὶ ἐκπίπτουσιν, ὅταν συγκριθῇ μᾶλλον συνιὸν δ' ἔτι χάσμα δοκεῖ. 50 'Chasms' get their appearance of depth from light breaking out of a dark blue or black mass of air. When the process of condensation goes further in such a case we often find 'torches' ejected. When the 'chasm' contracts it presents the appearance of a 'trench'.
ὅλως δ' ἐν τῷ μέλανι τὸ λευκὸν πολλὰς ποιεῖ ποικιλίας, οἷον ἡ φλὸξ ἐν τῷ καπνῷ. ἡμέρας μὲν οὖν ὁ ἥλιος κωλύει, νυκτὸς δ' ἔξω τοῦ φοινικοῦ τὰ ἄλλα δι' ὁμόχροιαν οὐ φαίνεται. 51 In general, white in contrast with black creates a variety of colours; like flame, for instance, through a medium of smoke. But by day the sun obscures them, and, with the exception of crimson, the colours are not seen at night because they are dark.
περὶ μὲν οὖν τῶν διαθεόντων ἀστέρων καὶ τῶν ἐκπυρουμένων, ἔτι δὲ τῶν ἄλλων τῶν τοιούτων φασμάτων ὅσα ταχείας ποιεῖται τὰς φαντασίας, ταύτας ὑπολαβεῖν δεῖ τὰς αἰτίας. 52 These then must be taken to be the causes of 'shooting-stars' and the phenomena of combustion and also of the other transient appearances of this kind.
Postquam philosophus assignavit causam accensionum quae videntur moveri in aere, hic assignat causam quorundam aliorum nocte apparentium. Et circa hoc duo facit. 49. After assigning the cause of the conflagrations that are seen being moved in the air, the Philosopher here assigns the cause of certain other things that appear at night. About this he does two things:
Primo proponit illa quorum causas assignare intendit. Et dicit quod aliquando apparent in nocte, cum fuerit serenitas, phantasmata, idest apparitiones, in caelo; sicut hiatus, idest quaedam aperturae, ac si caelum esset apertum, et bothyni, idest voragines, quasi profundae aperturae, et etiam sanguinei colores. First, he enumerates the things whose causes he intends to assign and says that sometimes at night, when it is clear, "phantoms," i.e., apparitions, are visible in the heaven: for instance, "crevices," i.e., gashes, as though the sky were open, and "bothyni," i.e., chasms, as though deep breaches, and also "blood-red colors."
Secundo ibi: causa autem et in his etc., assignat causas horum. Et circa hoc duo facit: 50. Secondly, he assigns the causes of these things. About this he does two things:

primo assignat causam quare appareant praedicta;

secundo quare multa alia fiunt quae non apparent, ibi: omnino autem in nigro album et cetera.

First, he gives the cause of their appearance, at 50;

Secondly, why many other things occur that are not visible, at 52.

Circa primum duo facit: About the first he does two things:

primo assignat causam colorum;

secundo assignat causam hiatus et voraginis, ibi: hiatus autem et cetera.

First, he assigns the cause of the colors;

Secondly, the cause of the crevices and chasms, at 51.

Dicit ergo primo quod eadem causa est in his apparitionibus, quae etiam est ignitionum de quibus supra dictum est. Cum enim manifestum sit quod aer superior (quem supra dixit hypeccauma) sic disponitur quod in eo fiat ignitio; quae quidem aliquando talis est ut videatur ardere flamma, quandoque autem taliter fit ignitio ut videantur ferri titiones et sidera; nullum est inconveniens, cum incensiones fiant in aere multiformes, quod ille aer superior coloratus appareat omni genere colorum. He says therefore first [49] that the causes of these apparitions and of the conflagrations discussed earlier are the same. For since it is plain that the upper air (which he earlier called "fuel") is so disposed as to be able to be ignited, so that sometimes a flame appears to burn, and sometimes it is ignited to give the appearance of moving torches and stars, it is not strange (since many varieties of ignitings occur in the air) that the upper air should appear colored with every variety of color.
Duobus enim modis contingit quod aer aliquatenus inspissatus omnes modos colorum repraesentet: uno modo quando aliquod minus lumen, quod non sufficit totaliter illuminare, transparet per aliquem fumum aut vaporem spissiorem; alio modo quando fit repercussio luminis ad aliquem aerem aliquatenus inspissatum. Sed maxime ex istis duabus causis apparent in aere color puniceus et purpureus, idest rubeus et subrubeus: quia maxime hi colores apparent ex aliquo igneo et albo mixtis nigro. For there are two ways in which air somewhat thickened comes to represent all varieties of colors: one way is when a feeble light, which is not enough to illuminate fully, shines through smoke or thick vapor; another way is when light is reflected off somewhat thickened air. From these two causes especially, there appears in the air a crimson and purple color, i.e., reddish and sub-red — for these colors appear especially when things fiery and white are mixed with black.
Quae quidem mixtio potest fieri secundum duas supradictas causas: scilicet secundum superappositiones (quod supra dixit transparentiam minoris luminis per aliquod spissius), sicut sol et luna et alia astra apparent punicea in ortu et occasu et quasi subrubea, quando eorum lumen non est perfectum. Sed hoc dico si fuerit calor: quia quando est frigus, vapores sunt condensati, et magis obscurant lumen astrorum orientium vel occidentium, ut transparere non possit; quando autem est calor, exhalationes sunt rariores, et sic per eas lumen astrorum transparere potest. Et similiter si astra videantur mediante fumo, videntur talis coloris. Such a mixture can occur as a result of the two above-mentioned causes: namely, by "superapposition" (described above as a feeble light shining through something fairly thick — as when the sun and the moon and other stars appear crimson when they rise and set, and as though sub-red when their light is not perfect). But I say this, if heat is present: because when it is cold, vapors are condensed and obscure the light of rising and setting stars more, so that it cannot get through; but when it is hot, the exhalations are finer and permit the light of the stars to pass through. Likewise, if the stars are seen through smoke, they have this color.
Et secundum etiam aliam praedictam causam fit praedicta mixtio, scilicet per refractionem; cum illud ad quod fit refractio luminis (quod hic speculum dicit), sive sit nubes aquosa sive aliquid huiusmodi, fuerit tale ut non repraesentet figuram, sed colorem. Haec autem exponet cum de iride agetur. This mixture can also be produced by the other cause mentioned: namely, refraction, when the object from which the light is refracted (he here calls this object a "mirror"), whether it be a water-soaked cloud or something other of the same sort, is of such a nature as to reveal color but not shape. He will explain this, when it is question of the rainbow.
Assignat autem causam consequenter quare huiusmodi colores cito disparent et non multo tempore manent: quia scilicet causa apparitionis ipsorum est velox, idest cito pertransiens; aer enim non multo tempore manet similis, sed de facili ingrossatur vel subtiliatur. Then he explains why these colors quickly disappear and do not last long: it is because the cause of their appearance is "rapid,," i.e., quickly passes — for air does not maintain a given state very long, and becomes thick or fine very easily.
Deinde cum dicit: hiatus autem etc., assignat causam hiatus et voraginis. Et dicit quod cum lumen quod apparet in aere, discontinuatur ex aliquo obscuro et nigro, quod scilicet est propter aliquem vaporem magis spissum, apparet quod sit aliqua profunditas et apertura in caelo. Et huius signum est quod, cum ille vapor qui interrumpit lumen, magis inspissatur, ex talibus hiatibus exeunt vel excidunt titiones ignei, quasi calido expulso a frigore vaporem inspissante. Sed quando ille vapor obscurus, discontinuans lumen, concretus et inspissatus fuerit magis, facit videri maiorem profunditatem, quia album superatur a nigro: cum autem fuerit e converso, tunc videtur solum hiatus vel apertura. 51. Then [50] he assigns the cause of "crevices" and "chasms" and says that when light visible in air is interrupted by something dark, due to thicker vapor than usual, depths and openings seem to exist in the heaven. A sign of this is that, when the vapor which interrupts the light becomes thicker still, fiery torches emerge or fall from these "crevices," as though something hot were ejected by the coldness which thickens the vapor. But when that dark vapor which interrupts the light becomes still more condensed and thick, it causes a greater depth to appear, because the white is overcome by black; when the situation is just the opposite, then only a crevice or opening appears.
Patet ergo quod utraque apparitio, et colorum et hiatuum, habent similem causam, scilicet admixtionem adinvicem albi et nigri: sed color purpureus aut puniceus fit ex albo transparente per nigrum; hiatus autem et vorago ex nigro interrumpente album. It is plain, therefore, that both apparitions, i.e., that of colors and that of crevices, have a like cause, namely, black and white mixing together: but the purple or crimson color results from white shining through something black, whereas the crevices and chasms result from something black screening the white.
Deinde cum dicit: omnino autem in nigro album etc., ostendit quod multa huiusmodi fiunt quae non apparent. Et dicit quod album coniunctum nigro multas facit differentias colorum; sicut apparet de flamma in fumo, quae facit diversos colores, secundum quod fumus fuerit densior vel rarior. Sed de die sol sua claritate prohibet huiusmodi colores apparere: de nocte vero non apparent nisi rubeus, quia alii colores, sicut viridis et alii obscuriores, sunt similes colori noctis, propter obscuritatem. 52. Then [51] he shows that many things of this sort occur but are not visible. And he says that white joined with black produces many varieties of color, as appears with flame in smoke, which produces various colors depending on whether the smoke is thick or fine. But by day the sun's brightness prevents these colors from being seen: at night, however, only red appears, because the other colors, such as green and other darker colors, are on account of their darkness like the color of night.
Ultimo epilogat praedeterminata. Et dicit quod praedictas causas oportet existimare de astris discurrentibus et ignitis, et de aliis huiusmodi apparitionibus, quaecumque festinas faciunt phantasias, idest quaecumque pertranseuntes videntur absque magna mora temporis. Finally, he sums up what has been determined and says [52] that these must be taken as the causes of shooting-stars and fire-stars and like apparitions "that make hasty appearances," i.e., that are seen to pass by without lasting very long.

Lecture 9
The opinions of others concerning comets
Chapter 6
περὶ δὲ τῶν κομητῶν καὶ τοῦ καλουμένου γάλακτος λέγωμεν, διαπορήσαντες πρὸς τὰ παρὰ τῶν ἄλλων εἰρημένα πρῶτον. 53 Let us go on to explain the nature of comets and the 'milky way', after a preliminary discussion of the views of others.
Ἀναξαγόρας μὲν οὖν καὶ Δημόκριτός φασιν εἶναι τοὺς κομήτας σύμφασιν τῶν πλανήτων ἀστέρων, ὅταν διὰ τὸ πλησίον ἐλθεῖν δόξωσι θιγγάνειν ἀλλήλων. 54 Anaxagoras and Democritus declare that comets are a conjunction of the planets approaching one another and so appearing to touch one another.
τῶν δ' Ἰταλικῶν τινες καλουμένων Πυθαγορείων ἕνα λέγουσιν αὐτὸν εἶναι τῶν πλανήτων ἀστέρων, ἀλλὰ διὰ πολλοῦ τε χρόνου τὴν φαντασίαν αὐτοῦ εἶναι καὶ τὴν ὑπερβολὴν ἐπὶ μικρόν, ὅπερ συμβαίνει καὶ περὶ τὸν τοῦ Ἑρμοῦ ἀστέρα διὰ γὰρ τὸ μικρὸν ἐπαναβαίνειν πολλὰς ἐκλείπει φάσεις, ὥστε διὰ χρόνου φαίνεσθαι πολλοῦ. 55 Some of the Italians called Pythagoreans say that the comet is one of the planets, but that it appears at great intervals of time and only rises a little above the horizon. This is the case with Mercury too; because it only rises a little above the horizon it often fails to be seen and consequently appears at great intervals of time.
παραπλησίως δὲ τούτοις καὶ οἱ περὶ Ἱπποκράτην τὸν Χῖον καὶ τὸν μαθητὴν αὐτοῦ (343a.) Αἰσχύλον ἀπεφήναντο, πλὴν τήν γε κόμην οὐκ ἐξ αὑτοῦ φασιν ἔχειν, ἀλλὰ πλανώμενον διὰ τὸν τόπον ἐνίοτε λαμβάνειν ἀνακλωμένης τῆς ἡμετέρας ὄψεως ἀπὸ τῆς ἑλκομένης ὑγρότητος ὑπ' αὐτοῦ πρὸς τὸν ἥλιον. διὰ δὲ τὸ ὑπολείπεσθαι βραδύτατα τῷ χρόνῳ διὰ πλείστου χρόνου φαίνεσθαι τῶν ἄλλων ἄστρων, ὡς ὅταν ἐκ ταὐτοῦ φανῇ ὑπολελειμμένον ὅλον τὸν ἑαυτοῦ κύκλον ὑπολείπεσθαι δ' αὐτὸν καὶ πρὸς ἄρκτον καὶ πρὸς νότον. ἐν μὲν οὖν τῷ μεταξὺ τόπῳ τῶν τροπικῶν οὐχ ἕλκειν τὸ ὕδωρ πρὸς ἑαυτὸν διὰ τὸ κεκαῦσθαι ὑπὸ τῆς τοῦ ἡλίου φορᾶς πρὸς δὲ νότον ὅταν φέρηται, δαψίλειαν μὲν ἔχειν τῆς τοιαύτης νοτίδος, ἀλλὰ διὰ τὸ μικρὸν εἶναι τὸ ὑπὲρ τῆς γῆς τμῆμα τοῦ κύκλου, τὸ δὲ κάτω πολλαπλάσιον, οὐ δύνασθαι τὴν ὄψιν τῶν ἀνθρώπων φέρεσθαι κλωμένην πρὸς τὸν ἥλιον οὔτε τῷ τροπικῷ τόπῳ πλησιάζοντος οὔτ' ἐπὶ θεριναῖς τροπαῖς ὄντος τοῦ ἡλίου διόπερ ἐν τούτοις μὲν τοῖς τόποις οὐ γίγνεσθαι κομήτην αὐτόν ὅταν δὲ πρὸς βορέαν ὑπολειφθεὶς τύχῃ, λαμβάνειν κόμην διὰ τὸ μεγάλην εἶναι τὴν περιφέρειαν τὴν ἄνωθεν τοῦ ὁρίζοντος, τὸ δὲ κάτω μέρος τοῦ κύκλου μικρόν ῥᾳδίως γὰρ τὴν ὄψιν τῶν ἀνθρώπων ἀφικνεῖσθαι τότε πρὸς τὸν ἥλιον. 56 A view like theirs was also expressed by Hippocrates of Chios and his pupil Aeschylus. Only they say that the tail does not belong to the comet iself, but is occasionally assumed by it on its course in certain situations, when our sight is reflected to the sun from the moisture attracted by the comet. It appears at greater intervals than the other stars because it is slowest to get clear of the sun and has been left behind by the sun to the extent of the whole of its circle before it reappears at the same point. It gets clear of the sun both towards the north and towards the south. In the space between the tropics it does not draw water to itself because that region is dried up by the sun on its course. When it moves towards the south it has no lack of the necessary moisture, but because the segment of its circle which is above the horizon is small, and that below it many times as large, it is impossible for the sun to be reflected to our sight, either when it approaches the southern tropic, or at the summer solstice. Hence in these regions it does not develop a tail at all. But when it is visible in the north it assumes a tail because the arc above the horizon is large and that below it small. For under these circumstances there is nothing to prevent our vision from being reflected to the sun.
Postquam philosophus determinavit de stellis cadentibus et similibus, hic determinat de cometis. 53. After determining concerning falling stars and the like, the Philosopher now determines about comets.
Et primo dicit de quo est intentio: dicens quod nunc dicendum est de cometis et lacteo circulo, hoc ordine servato circa utrumque, ut primo inferamus dubitationes, idest obiectiones, ad ea quae dicta sunt ab aliis, et postea determinemus quod nobis videtur. Secundo ibi: Anaxagoras quidem igitur etc., prosequitur propositum ordine praemisso. First, he states his intention [53] and says that we must speak now of comets and the milky circle, observing with respect to each the following order: first, we shall present the "doubts," i.e., the objections to what others have said, and then we shall state what we think. Secondly [54], he pursues his proposition in the order stated.

Unde primo ponit opiniones aliorum de cometis;

secundo determinat de eis secundum opinionem suam, ibi: quoniam autem de immanifestis et cetera.

First, therefore, he presents what others thought of comets;

Secondly, he determines about them according to his own opinion (L. 11).

Prima dividitur in duas: The first is divided into two parts:

in prima ponit opiniones;

in secunda improbat eas, ibi: omnibus autem et cetera.

In the first he presents the opinions;

In the second he disproves them (L. 10).

Prima dividitur in tres, secundum tres opiniones quas ponit. The first is divided into three parts according to the three opinions he presents.
Primo ergo ponit opinionem Anaxagorae et Democriti, qui dixerunt cometas esse symphasim, idest coapparitionem, stellarum errantium. Quae sunt quinque, scilicet Saturnus, Iupiter, Mars, Venus et Mercurius; quarum aliquae, cum appropinquant adinvicem, videntur se tangere; et ita videtur una stella, et apparet ei coma, propter augmentum luminis. 54. First therefore [54], he gives the opinion of Anaxagoras and Democritus who said that comets are "symphases," i.e., co-appearances of [planets] the wandering stars. These are five in number (namely, Saturn, Jupiter, Mars, Venus and Mercury), some of which, as they approach one another seem to touch, and there seems to be one star, and "flowing hair" appears [the coma, hence "comet"], due to the increase of light.
Secundam opinionem ponit ibi: Italicorum autem et cetera. Et fuit quorundam Pythagoricorum in Italia commorantium, qui dixerunt cometam esse unam de stellis errantibus; sed non esse phantasiam, idest visionem, eius, nisi post multum tempus, propter hoc quod excedit, idest recedit a sole, modicum; sicut et accidit circa stellam Mercurii, quae quia modicum digreditur, idest elongatur a sole, frequenter non apparet, ita quod post longum tempus appareat, cum diu non apparuit. 55. He presents the second opinion [55], which was that of certain Pythagoreans living in Italy who said that a comet is one of the wandering stars [planets], but that the "phantasy," i.e., vision, of it occurs only after a long lapse of time, because it "exceeds," i.e., departs from the sun only slightly — as is the case with the star Mercury, which, because it only slightly "digresses from," i.e., moves away from, the sun, frequently does not appear, appearing only after a long time, having for a long time not appeared.
Tertiam opinionem ponit ibi: similiter his etc.: quae fuit quorundam sequentium Hippocratem et Aeschylum eius discipulum. Quae quidem opinio in hoc similis est secundae, quod posuit stellam cometam esse unam de errantibus: sed in hoc differt ab ea, quod secunda opinio posuit quod illa stella erratica habet comam ex se; sed ista tertia opinio ponit quod non habet comam ex seipsa, sed cum sit errans, ex loco aliquando accipit comam. Quia dicebant quod ab ipsa stella attrahitur quidam humor; et cum ponerent quod visus fieret extramittendo, posuerunt quod radius visualis pertingens ad illum humorem attractum ab ea, repercutitur usque ad solem; et sic ille vapor attractus est quasi quoddam speculum igneum solis (nam repercussio est causa quod aliquid in speculo videatur); et ita dicunt fieri comam. 56. He presents the third opinion [56], which was that of certain followers of Hippocrates, and of Aeschylus, his disciple. This opinion is similar to the second in supposing that a comet is one of the wandering stars; it differs in that the second opinion held the wandering star had a tail [coma] of itself, whereas this third opinion holds that it does not have a tail of itself, but, since it is wandering, sometimes acquires a tail by its position. According to this opinion a certain moisture is attracted by the star, and, since they assume that vision occurs by a beholder emitting visual rays, they posited that a visual ray reaches that moisture attracted by the star and is then reflected toward the sun. In this way the attracted vapor acts as a certain fiery mirror for the sun (for things are visible in a mirror because of reflection); and they say that it is thus that the tail is formed.
Assignat autem consequenter causam de tempore apparitionis. Et dicit quod stella cometa apparet post plurimum tempus aliorum astrorum, idest magis occultatur quam aliquae aliae stellae, quia tardissime discedit a sole secundum tempus, videlicet cum peregerit totum suum circulum. Quod appellat subdeficere: dicuntur enim stellae errantes subdeficere respectu primi motus; vel quia moventur motu contrario, et sic videntur secundum proprium motum posteriorari; vel quia, sicut quidam dixerunt, tardius moventur quam primum caelum, quod revolvit omnia motu diurno. Sic autem dicebant quod stella cometa subdeficit a sole, totum suum circulum peragendo: et ideo, cum redierit ad illum terminum ex quo incoepit discedere, iterum apparet, quousque iterum coniungatur soli. Et dicebant etiam quod ista stella in suo motu recedit a sole, non tantum secundum longitudinem, sed etiam secundum latitudinem, declinans ad arctum et Austrum, idest ad Septentrionem et meridiem. 57. Then he assigns the cause regulating the time of its appearance and says that a comet star "appears at greater intervals than the other stars," i.e., is rendered invisible longer than the other stars, because time-wise it is very slow in getting clear of the sun, i.e., only when it has completed its entire cycle. He calls this "being left behind": for the wandering stars are said to be "left behind" with respect to the first motion, either because they are moved in a contrary direction and thus seem to retreat by their own motion, or because, as some say, they are moved more slowly than the first heaven which in its diurnal motion revolves everything else. So they said that a comet star is left behind by the sun to the extent of the whole of its orbit; and therefore, when it returns to the point where it first began to recede, it appears once more and remains in view until it again gets in conjunction with the sun. They also said that this star moves away from the sun not only according to longitude, but also according to latitude, declining to the north and south winds, i.e., to the north and to the south.
Assignat etiam consequenter causam circa locum apparitionis huius stellae. Et dicit quod haec stella non apparet in medio duorum tropicorum, scilicet cancri et Capricorni: quia per illam partem caeli movetur sol et consumit humiditatem, unde in ea parte caeli non potest praedicta stella attrahere aquam. Sed cum declinat ad Austrum, recedens a via solis, invenit copiam ibi talis humiditatis, eo quod non est consumpta a sole. Sed propter obliquitatem horizontis, nobis qui habitamus in parte Septentrionali, pars circuli paralleli quae est supra terram est parva, quae autem est sub terra est maior: et sic sol, qui de nocte, cum videtur cometa, est sub terra, tantum distat ab humore attracto a stella, quod non potest visus hominum repercuti ab humore ad solem; neque si sol sit propinquus tropico, scilicet Capricorno, neque si sit in aestivis versionibus, idest in tropico aestivo, qui est cancer. Ubicumque enim fuerit sol sub terra, erit maior distantia eius ad vaporem contractum quam sit conveniens repercussioni, vel ex circulo, vel ex latitudine zodiaci. Sed quando stella illa relinquitur a sole versus Boream, idest ad Septentrionalem partem, tunc potest recipere comam: quia ibi est multum de humiditate, et peripheria circuli quae est super horizontem est ibi magna, et quae est subtus est parva, et sic de facili visus hominum refractus potest pertingere ad solem. 58. He also assigns the cause regarding the place of this star's appearance. And he says that this star does not appear in between the two tropics, namely, of Cancer and Capricorn; for the sun travels through that portion of the heaven and consumes the moisture, so that in that portion of the heaven this star cannot attract any water. But when it shifts to the south, receding from the sun's course, it finds there an abundance of moisture, because it had not been consumed by the sun. But because of the obliquity of the horizon, for us who live in the north the part of its parallel circle which is above the earth is small, whereas the part below is larger; consequently, the sun which, at night, when comets are visible, is under the earth, is so far from the moisture attracted by the star that a man's vision cannot be reflected from the moisture to the sun — whether the sun is near the "tropic," namely, that of Capricorn, or whether it is in the "summer turnings," i.e., in the summer tropic, which is that of Cancer. For no matter where the sun is under the earth, its distance from the contracted vapor is too great for reflection, either from the circle or from the latitude of the zodiac. But when that star is left behind by the sun toward the "boreal" [north wind], i.e., the north, then it can acquire a tail — because there is there much moisture, and the circumference of its circle above the horizon is large there, whereas the part below is small. Consequently it is easy for man's reflected vision to reach the sun.

Lecture 10
Refutation of these opinions
Chapter 6 cont.
πᾶσιν δὲ τούτοις τὰ μὲν κοινῇ συμπίπτει λέγειν ἀδύνατα, τὰ δὲ χωρίς. 57 These views involve impossibilities, some of which are common to all of them, while others are peculiar to some only.
πρῶτον μὲν οὖν τοῖς λέγουσιν ὅτι τῶν πλανωμένων ἐστὶν εἷς ἀστέρων ὁ κομήτης οἱ γὰρ πλανώμενοι πάντες ἐν τῷ κύκλῳ ὑπολείπονται τῷ τῶν ζῳδίων, κομῆται δὲ πολλοὶ ἑωραμένοι εἰσὶν ἔξω τοῦ κύκλου. εἶτα καὶ πλείους ἑνὸς ἅμα γεγένηνται πολλάκις. 58 This is the case, first, with those who say that the comet is one of the planets. For all the planets appear in the circle of the zodiac, whereas many comets have been seen outside that circle. Again more comets than one have often appeared simultaneously.
πρὸς δὲ τούτοις, εἰ διὰ τὴν ἀνάκλασιν τὴν κόμην ἴσχουσι, καθάπερ φησὶν Αἰσχύλος καὶ Ἱπποκράτης, ἔδει ποτὲ φαίνεσθαι καὶ ἄνευ κόμης τὸν ἀστέρα τοῦτον, ἐπειδήπερ ὑπολείπεται μὲν καὶ εἰς ἄλλους τόπους, τὴν δὲ κόμην ἴσχει οὐ πανταχοῦ νῦν δ' οὐδεὶς ὦπται παρὰ τοὺς πέντε ἀστέρας οὗτοι δὲ πολλάκις ἅμα πάντες μετέωροι φαίνονται ὑπὲρ τοῦ ὁρίζοντος. καὶ φανερῶν δὲ ὄντων αὐτῶν ἁπάντων καὶ μὴ φαινομένων πάντων, ἀλλ' ἐνίων ὄντων πρὸς τῷ ἡλίῳ, οὐδὲν ἧττον κομῆται φαίνονται γιγνόμενοι πολλάκις. 59 Besides, if their tail is due to reflection, as Aeschylus and Hippocrates say, this planet ought sometimes to be visible without a tail since, as they it does not possess a tail in every place in which it appears. But, as a matter of fact, no planet has been observed besides the five. And all of them are often visible above the horizon together at the same time. Further, comets are often found to appear, as well when all the planets are visible as when some are not, but are obscured by the neighbourhood of the sun.
ἀλλὰ μὴν οὐδὲ τοῦτο ἀληθές, ὡς ἐν τῷ πρὸς ἄρκτον τόπῳ γίγνεται κομήτης μόνον, ἅμα καὶ τοῦ ἡλίου (343b.) ὄντος περὶ θερινὰς τροπάς ὅ τε γὰρ μέγας κομήτης ὁ γενόμενος περὶ τὸν ἐν Ἀχαΐᾳ σεισμὸν καὶ τὴν τοῦ κύματος ἔφοδον ἀπὸ δυσμῶν τῶν ἰσημερινῶν ἀνέσχεν, καὶ πρὸς νότον ἤδη πολλοὶ γεγόνασιν. 60 Moreover the statement that a comet only appears in the north, with the sun at the summer solstice, is not true either. The great comet which appeared at the time of the earthquake in Achaea and the tidal wave rose due west; and many have been known to appear in the south.
ἐπὶ δ' ἄρχοντος Ἀθήνησιν Εὐκλέους τοῦ Μόλωνος ἐγένετο κομήτης ἀστὴρ πρὸς ἄρκτον μηνὸς Γαμηλιῶνος περὶ τροπὰς ὄντος τοῦ ἡλίου χειμερινάς καίτοι τοσοῦτον ἀνακλασθῆναι καὶ αὐτοὶ τῶν ἀδυνάτων εἶναί φασι. 61 Again in the archonship of Euclees, son of Molon, at Athens there appeared a comet in the north in the month Gamelion, the sun being about the winter solstice. Yet they themselves admit that reflection over so great a space is an impossibility.
κοινὸν δὲ καὶ τούτοις καὶ τοῖς τὴν σύναψιν λέγουσιν πρῶτον μὲν ὅτι καὶ τῶν ἀπλανῶν λαμβάνουσι κόμην τινές. καὶ τοῦτ' οὐ μόνον Αἰγυπτίοις πιστεῦσαι δεῖ, καίτοι κἀκεῖνοί φασιν, ἀλλὰ καὶ ἡμεῖς ἐφεωράκαμεν τῶν γὰρ ἐν τῷ ἰσχίῳ τοῦ κυνὸς ἀστήρ τις ἔσχε κόμην, ἀμαυρὰν μέντοι ἀτενίζουσιν μὲν γὰρ εἰς αὐτὸν ἀμυδρὸν ἐγίγνετο τὸ φέγγος, παραβλέπουσι δ' ἠρέμα τὴν ὄψιν πλέον. 62 An objection that tells equally against those who hold this theory and those who say that comets are a coalescence of the planets is, first, the fact that some of the fixed stars too get a tail. For this we must not only accept the authority of the Egyptians who assert it, but we have ourselves observed the fact. For a star in the thigh of the Dog had a tail, though a faint one. If you fixed your sight on it its light was dim, but if you just glanced at it, it appeared brighter.
πρὸς δὲ τούτοις ἅπαντες οἱ καθ' ἡμᾶς ὠμμένοι ἄνευ δύσεως ἠφανίσθησαν ἐν τῷ ὑπὲρ τοῦ ὁρίζοντος τόπῳ ἀπομαρανθέντες κατὰ μικρὸν οὕτως, ὥστε μήτε ἑνὸς ἀστέρος ὑπολειφθῆναι σῶμα μήτε πλειόνων, ἐπεὶ καὶ ὁ μέγας ἀστὴρ περὶ οὗ πρότερον ἐμνήσθημεν ἐφάνη μὲν χειμῶνος ἐν πάγοις καὶ αἰθρίαις ἀφ' ἑσπέρας, ἐπὶ Ἀστείου ἄρχοντος, καὶ τῇ μὲν πρώτῃ οὐκ ὤφθη ὡς προδεδυκὼς τοῦ ἡλίου, τῇ δ' ὑστεραίᾳ ὤφθη ὅσον ἐνδέχεται γὰρ ἐλάχιστον ὑπελείφθη, καὶ εὐθὺς ἔδυ τὸ δὲ φέγγος ἀπέτεινε μέχρι τοῦ τρίτου μέρους τοῦ οὐρανοῦ οἷον ἅλμα διὸ καὶ ἐκλήθη ὁδός. ἐπανῆλθε δὲ μέχρι τῆς ζώνης τοῦ Ὠρίωνος, καὶ ἐνταυθοῖ διελύθη. καίτοι Δημόκριτός γε προσπεφιλονείκηκεν τῇ δόξῃ τῇ αὑτοῦ φησὶ γὰρ ὦφθαι διαλυομένων τῶν κομητῶν ἀστέρας τινάς. τοῦτο δὲ οὐχ ὁτὲ μὲν ἔδει γίγνεσθαι ὁτὲ δὲ οὔ, ἀλλ' ἀεί. πρὸς δὲ τούτοις καὶ οἱ Αἰγύπτιοί φασι καὶ τῶν πλανήτων καὶ πρὸς αὑτοὺς καὶ πρὸς τοὺς ἀπλανεῖς γίγνεσθαι συνόδους, καὶ αὐτοὶ ἑωράκαμεν τὸν ἀστέρα τὸν τοῦ Διὸς τῶν ἐν τοῖς διδύμοις συνελθόντα τινὶ ἤδη καὶ ἀφανίσαντα, ἀλλ' οὐ κομήτην γενόμενον. 63 Besides, all the comets that have been seen in our day have vanished without setting, gradually fading away above the horizon; and they have not left behind them either one or more stars. For instance the great comet we mentioned before appeared to the west in winter in frosty weather when the sky was clear, in the archonship of Asteius. On the first day it set before the sun and was then not seen. On the next day it was seen, being ever so little behind the sun and immediately setting. But its light extended over a third part of the sky like a leap, so that people called it a 'path'. This comet receded as far as Orion's belt and there dissolved. Democritus however, insists upon the truth of his view and affirms that certain stars have been seen when comets dissolve. But on his theory this ought not to occur occasionally but always.
ἔτι δὲ καὶ ἐκ τοῦ λόγου φανερόν οἱ γὰρ ἀστέρες κἂν εἰ μείζους καὶ ἐλάττους φαίνονται, ἀλλ' ὅμως ἀδιαίρετοί γε καθ' ἑαυτοὺς εἶναι δοκοῦσιν. 64 Besides, the Egyptians affirm that conjunctions of the planets with one another, and with the fixed stars, take place, and we have ourselves observed Jupiter coinciding with one of the stars in the Twins and hiding it, and yet no comet was formed.
ὥσπερ οὖν καὶ εἰ ἦσαν ἀδιαίρετοι, ἁψάμενοι οὐδὲν ἂν ἐποίησαν μέγεθος μεῖζον, οὕτως καὶ ἐπειδὴ οὐκ εἰσὶν μὲν φαίνονται δὲ (344a.) ἀδιαίρετοι, καὶ συνελθόντες οὐδὲν φανοῦνται μείζους τὸ μέγεθος ὄντες. 65 Further, we can also give a rational proof of our point. It is true that some stars seem to be bigger than others, yet each one by itself looks indivisible. Consequently, just as, if they really had been indivisible, their conjunction could not have created any greater magnitude, so now that they are not in fact indivisible but look as if they were, their conjunction will not make them look any bigger.
ὅτι μὲν οὖν αἱ λεγόμεναι περὶ αὐτῶν αἰτίαι ψευδεῖς οὖσαι τυγχάνουσιν, εἰ μὴ διὰ πλειόνων, ἀλλὰ καὶ διὰ τούτων ἱκανῶς δῆλόν ἐστιν. 66 Enough has been said, without further argument, to show that the causes brought forward to explain comets are false.
Positis opinionibus, hic improbat eas. 59. Having presented the opinions, he now disproves them.

Et primo ponit modum improbandi: et dicit quod quaedam intendit inducere quae sunt communiter contra omnes praedictas opiniones, quaedam vero quae sunt contra aliquam earum specialiter tantum.

First, he declares how they are to be disproved [57] and says that he intends to present certain facts against all the opinions as a group, and certain facts against one or other of them in particular.

Secondly, he disputes against the opinions presented.

Secundo ibi: primo quidem igitur etc., disputat contra positas opiniones: et primo contra secundam, quae fuit Pythagoricorum;

secundo contra tertiam, quae fuit Hippocratis, ibi: adhuc autem si propter etc.;

tertio contra primam, quae fuit Democriti et Anaxagorae, ibi: commune autem et his et cetera.

First, against the second one, which was that of the Pythagoreans;

Secondly, against the third, which was Hippocrates', at 61;

Thirdly, against the first, which was that of Democritus and Anaxagoras, 64b.

Circa primum ponit duas rationes: quarum prima talis est. Omnes stellae erraticae subdeficiunt, idest moventur quasi subdeficiendo, sicut expositum est, in circulo animalium qui dicitur zodiacus; sed multi cometae visi sunt extra hunc circulum; ergo non omnes cometae sunt stellae erraticae. 60. As to the first [58] he gives two arguments: the first of which is that all the wandering stars are "left behind," i.e., move as though being left behind, as already explained, in the "circle of animals called the "Zodiac"; on the other hand, many comets are found outside this circle. Therefore, not all comets are wandering stars.
Secunda ratio talis est. Saepe visi sunt cometae plures uno simul facti: non igitur cometa est una stellarum errantium. Harum rationum prima est communis contra has opiniones: secunda est propria contra secundam et tertiam opinionem. The second argument is this: more comets than one have often been seen together; hence a comet is not one of the wandering stars. The first of these arguments is against these opinions together; the second is specifically against the second and third opinions.
Deinde cum dicit: adhuc autem si propter etc., improbat opinionem Hippocratis per tres rationes. Circa quarum primam dicit quod, si aliquis planetarum propter refractionem visus habet comam, sicut dixit Hippocrates, oporteret quod aliquando haec stella erratica appareret sine coma. Et hoc ideo, quia non ubique habet comam, ut dictum est, sed solum cum est extra tropicos, declinans ad Septentrionem: manifestum est autem quod etiam in aliis locis subdeficit, quasi discedens a sole; et ita oportet quod aliquando videatur sine coma. Sed nulla stella visa est sine coma errans praeter quinque stellas supra nominatas; quae quandoque omnes apparent simul elevatae super horizontem, et omnibus eis existentibus super horizontem, vel etiam quibusdam earum apparentibus super horizontem et quibusdam existentibus cum sole, nihilominus apparent cometae. Et sic manifestum est quod non semper cometa est una quinque stellarum errantium. Et nulla est alia sine coma praeter has. Ergo cometa non est stella errans, quandoque sine coma apparens: quod oporteret si comam ex seipso non haberet, sed ex aliquo loco determinato, ut ipsi dicunt. 61. Then [59] he disproves the opinion of Hippocrates with three arguments. As to the first of these he says that if a planet has a tail because of the reflection of the sight, as Hippocrates said, then it would have occasionally to appear without a tail. This is because it does not everywhere have a tail, as was said, but only when it is outside the tropics, receding to the north — for it is plain that it "falls behind" in other places as though receding from the sun; consequently it must sometimes appear without a tail. But no star is seen wandering without a tail other than the above-mentioned five. But occasionally all five are visible above the horizon at the same time; and when all are above the horizon, or some appear above and some are with the sun, comets nevertheless appear. Hence it is plain that a comet is not always one of the five wandering stars. And there is no other without a tail than these [five]. Therefore a comet is not a wandering star, which on occasion appears with a tail — which would have to be the case, if it did not possess a tail of itself but from being in some determined place, as they claim.
Secundam rationem ponit ibi: at vero neque hoc verum et cetera. Et dicit quod non est verum quod cometa fiat solum in loco qui declinat ad Septentrionem, hoc simul observato quod sol tunc sit circa tropicos aestivales, quasi propinquius stellae. Quia magnus cometes qui factus est eo tempore quo fuit factus terraemotus magnus in Achaia et supergressio fluctuum, ortus fuit ab occasibus aequinoctialibus: et ita manifestum est quod fuit infra tropicos. Et iam etiam multi facti sunt ad Austrum. Falsum est ergo quod dicunt, quod fiat tantum ad Septentrionem. 62. He gives the second argument [60] and says that it is not true to say that a comet occurs only in the region toward the north with the additional observation of the sun at the summer tropics [i.e., summer solstice], as though nearer to the comet. For the great comet which appeared at the time of the great earthquake and tidal wave in Achaia arose from the western equator; so it is plain that it occurred within the "tropics." Moreover, many have appeared in the south. It is therefore false to say that they occur only toward the north.
Tertiam rationem ponit ibi: sub principe autem et cetera. Et dicit quod tempore cuiusdam principis Atheniensium, facta fuit stella cometa, sole existente circa tropicos hiemales, idest circa Capricornum, et hoc mense Gamelione, idest Decembri vel Ianuario. Et hoc videtur esse impossibile, sicut etiam ipsi dicunt, quod fiat tanta refractio visus nostri ad solem, propter distantiam eius quae est tunc temporis de nocte ad solem, et propter magnitudinem decisionis circuli qui est sub horizonte. Falsum est ergo quod dicunt, quod non appareat cometa nisi sole existente circa tropicum aestivalem. 63. He gives a third argument [61] and says that in the time of a certain Athenian ruler, a comet star was formed when the sun was near the winter tropics [solstice], i.e., near Capricorn and this was in the month of "Gamelion," i.e., December or January. Now as they themselves admit, it seems impossible for such a long reflection from our vision to the sun to occur, considering the distance to the sun then prevailing at night and considering the size of the section of the circle below the horizon. Therefore, their claim that a comet does not appear unless the sun is near the summer tropic [solstice] is false.
Deinde cum dicit: commune autem et his etc., improbat primam opinionem per quatuor rationes. Quarum prima est contra omnes praedictas opiniones dicentes cometas esse stellas erraticas: quia etiam quaedam stellarum non errantium accipiunt comam. Et hoc non solum oportet credere Aegyptiis studentibus in mathematicis, qui hoc dicunt; sed ipse Aristoteles dicit se hoc vidisse, quod una stellarum quae est in figuratione canis, apud femur eius, comam habuit, sed debilem: quod patuit quia, quando aliquis fortiter intendebat in ipsam, debilitabatur lumen comae; sed quando aliquis iaciebat visum in stellam non nimis intense et remissius, plus apparebat lumen comae. 64. Then [62] he disproves the first opinion with four arguments. The first of these is against all the aforesaid opinions that claim the comets are wandering stars — for even certain stars that are not wandering receive a tail. And this is to be believed not only on the authority of certain Egyptians devoted to mathematics, but Aristotle himself says that he saw one of the stars in the constellation of the Dog, in the thigh, to be exact, with a tail, although it was faint: this was evidenced by the fact that when you gazed at it intently, the light of the tail grew dim, but when one glanced at the star not too intensely but more moderately, more of the tail's light appeared.
Secundam rationem ponit ibi: adhuc autem omnes et cetera. Et dicit quod omnes cometae qui suo tempore fuerunt visi, disparuerunt in loco super horizontem sine occasu, idest sine appropinquatione ad solem. Tunc enim dicitur occasus stellarum, quando intrant sub radiis solis: sed cometae apparentes suo tempore, disparuerunt sine hoc quod appropinquarent ad solem, adhuc super horizontem existentes longe a sole. Et disparuerunt quasi paulatim consumpti, ita quod non derelinqueretur neque corpus unius stellae neque plurium. Quia magna stella de qua supra diximus quod fuit tempore terraemotus in Achaia, apparuit tempore hiemis in vespere, existente gelu et serenitate, sub Astio principe Atheniensium; et primo die non apparuit ipsa stella, sed solum coma eius, quasi occidens ante solem; secundo autem die apparuit quantum possibile fuit, quia per modicum tempus remansit post solem et mox occubuit; sed lumen cometa extendit usque ad tertiam partem caeli, quasi simul et non paulatim crescens in lumine, ita ut ille ascensus luminis vocatus fuerit via cometae; et ascendit etiam, retrocedens a sole, usque ad quasdam stellas quae vocantur zona Orionis, et ibi fuit dissoluta, non appropinquando ad solem, sed magis ac magis discedendo ab eo. 65. In the second argument [63] he says that all the comets that were seen in his time disappeared in a region above the horizon "without setting," i.e., without approaching the sun. For stars are said to "set" when they enter into the sun's rays; but the comets of his time disappeared without approaching the sun, still being above the horizon far from the sun. And they disappeared as if gradually wasting away without leaving behind the body of one star or of several. For the great star previously described, which was at the time of the earthquake in Achaia, in the Athenian archonship of Astius, appeared in winter during the evening when it was frosty and clear: on the first day, not the star, but only its tail, appeared, as though setting before the sun; but on the second day it was as visible as conditions permitted, because for a short time it remained behind the sun and then immediately set; but the light of that comet spread over a third part of the heaven which burst into light not gradually but all at once, so that the upward ascent of the light was called the comet's path; it did indeed ascend, receding from the sun toward the stars called "Orion's belt," where it was dissolved, not by approaching the sun, but by receding farther and farther from it.
Haec etiam ratio est contra omnes opiniones praedictas, quae dicunt cometam esse unam vel plures stellarum errantium. Et sic patet per hanc rationem quod illud quod Democritus dixit ad confirmandam suam opinionem, non fuit sufficiens. Dixit enim quod, dissolutis cometis, aliquando apparuerunt stellae quaedam remanentes: quod ideo est insufficiens, quia oportebat ipsum probare quod, non aliquando, sed semper remanserunt stellae dissolutis cometis; quod apparet esse falsum ex eo quod dictum est. This is also an argument against all the foregoing opinions that say a comet is one or more of the wandering stars. Consequently, it is plain from this argument that what Democritus said in support of his opinion was insufficient. For he said that when comets dissolved, there sometimes appeared certain remaining stars. This is an insufficient explanation because it devolved on him to prove that stars always, and not just occasionally, remained when comets were dissolved — which has been seen to be false from what has been said.
Tertiam rationem ponit ibi: adhuc autem et Aegyptii etc.: quae talis est. Aegyptii dicunt quod fiunt coniunctiones stellarum errantium adinvicem et ad alias stellas fixas. Et dicit se vidisse stellam Iovis se supposuisse cuidam stellae quae est in geminis, ita quod fecit eam disparere. Sed tamen non fuit factus cometa: quod oporteret secundum opinionem Democriti et Anaxagorae. 66. He gives a third argument [64] which is this: Egyptians claim that the conjunctions of the planets with one another and with certain fixed stars take place. And he says that he himself saw Jupiter conjoin with a star in Gemini and make it invisible. Yet no comet was formed, as should have according to the opinion of Democritus and Anaxagoras.
Quartam rationem ponit ibi: adhuc autem et ex ratione etc.: quae talis est. Quamvis stellarum quaedam videantur esse maiores et quaedam minores adinvicem comparatae, tamen unaquaeque secundum se considerata videtur quasi punctalis et indivisibilis. Sed si essent vere indivisibiles, se invicem tangentes non facerent maiorem magnitudinem, ut probatum est in VI Physic. Ergo quando videntur indivisibiles licet non sint, quando coniunguntur adinvicem, non debent videri maiores secundum apparentem magnitudinem. Et ita ex contactu stellarum non debet videri coma, quasi propter augmentum luminis. Hae autem duae ultimae rationes sunt proprie contra opinionem Democriti. Ultimo autem recolligit illud quod dictum est: et patet in littera. 67. The fourth argument [65] is this: Although some stars seem to be larger and some smaller when compared to one another, yet each considered by itself appears to be as though a point and indivisible. But if they were in very truth indivisible, they could not produce a larger magnitude by merely touching one another, as was proved in Physics VI. Therefore, when they seem to be indivisibles, although they are not, they should not, when in conjunction, seem larger as far as their apparent size is concerned. Consequently, from the conjunction of stars a tail should not be visible as though produced by an increase of light. (These last two arguments are properly against Democritus' opinion). Finally, he summarizes what has been said — as is had in text [66].

Lecture 11
The cause, time and place of the appearance of comets according to Aristotle
Chapter 7
ἐπεὶ δὲ περὶ τῶν ἀφανῶν τῇ αἰσθήσει νομίζομεν ἱκανῶς ἀποδεδεῖχθαι κατὰ τὸν λόγον, ἐὰν εἰς τὸ δυνατὸν ἀναγάγωμεν, 67 We consider a satisfactory explanation of phenomena inaccessible to observation to have been given when our account of them is free from impossibilities.
ἔκ τε τῶν νῦν φαινομένων ὑπολάβοι τις ἂν ὧδε περὶ τούτων μάλιστα συμβαίνειν ὑπόκειται γὰρ ἡμῖν τοῦ κόσμου τοῦ περὶ τὴν γῆν, ὅσον ὑπὸ τὴν ἐγκύκλιόν ἐστιν φοράν, εἶναι τὸ πρῶτον μέρος ἀναθυμίασιν ξηρὰν καὶ θερμήν αὕτη δὲ αὐτή τε καὶ τοῦ συνεχοῦς ὑπ' αὐτὴν ἀέρος ἐπὶ πολὺ συμπεριάγεται περὶ τὴν γῆν ὑπὸ τῆς φορᾶς καὶ τῆς κινήσεως τῆς κύκλῳ φερομένη δὲ καὶ κινουμένη τοῦτον τὸν τρόπον, ᾗ ἂν τύχῃ εὔκρατος οὖσα, πολλάκις ἐκπυροῦται διό φαμεν γίγνεσθαι καὶ τὰς τῶν σποράδων ἀστέρων διαδρομάς. 68 The observations before us suggest the following account of the phenomena we are now considering. We know that the dry and warm exhalation is the outermost part of the terrestrial world which falls below the circular motion. It, and a great part of the air that is continuous with it below, is carried round the earth by the motion of the circular revolution. In the course of this motion it often ignites wherever it may happen to be of the right consistency, and this we maintain to be the cause of the 'shooting' of scattered 'stars'.
ὅταν οὖν εἰς τὴν τοιαύτην πύκνωσιν ἐμπέσῃ διὰ τὴν ἄνωθεν κίνησιν ἀρχὴ πυρώδης, μήτε οὕτω πολλὴ λίαν ὥστε ταχὺ καὶ ἐπὶ πολὺ ἐκκαίειν, μήθ' οὕτως ἀσθενὴς ὥστε ἀποσβεσθῆναι ταχύ, ἀλλὰ πλείων καὶ ἐπὶ πολύ, ἅμα δὲ κάτωθεν συμπίπτῃ ἀναβαίνειν εὔκρατον ἀναθυμίασιν, ἀστὴρ τοῦτο γίγνεται κομήτης, ὅπως ἂν τὸ ἀναθυμιώμενον τύχῃ ἐσχηματισμένον ἐὰν μὲν γὰρ πάντῃ ὁμοίως, κομήτης, ἐὰν δ' ἐπὶ μῆκος, καλεῖται πωγωνίας. 69 We may say, then, that a comet is formed when the upper motion introduces into a gathering of this kind a fiery principle not of such excessive strength as to burn up much of the material quickly, nor so weak as soon to be extinguished, but stronger and capable of burning up much material, and when exhalation of the right consistency rises from below and meets it. The kind of comet varies according to the shape which the exhalation happens to take. If it is diffused equally on every side the star is said to be fringed, if it stretches out in one direction it is called bearded.
ὥσπερ δὲ ἡ τοιαύτη φορὰ ἀστέρος φορὰ δοκεῖ εἶναι, οὕτως καὶ ἡ μονὴ ἡ ὁμοία ἀστέρος μονὴ δοκεῖ εἶναι παραπλήσιον γὰρ τὸ γιγνόμενον οἷον εἴ τις εἰς ἀχύρων θημῶνα καὶ πλῆθος ὤσειε δαλὸν ἢ πυρὸς ἀρχὴν ἐμβάλοι μικράν φαίνεται γὰρ ὁμοία καὶ ἡ τῶν ἀστέρων διαδρομὴ τούτῳ ταχὺ γὰρ διὰ τὴν εὐφυΐαν τοῦ ὑπεκκαύματος διαδίδωσιν ἐπὶ μῆκος. εἰ δὴ τοῦτο μείνειε καὶ μὴ καταμαρανθείη διελθόν, ᾗ μάλιστα ἐπύκνωσε τὸ ὑπέκκαυμα, γένοιτ' ἂν ἀρχὴ τῆς φορᾶς ἡ τελευτὴ τῆς διαδρομῆς. τοιοῦτον ὁ κομήτης ἐστὶν ἀστήρ, ὥσπερ διαδρομὴ ἀστέρος, ἔχων ἐν ἑαυτῷ πέρας καὶ ἀρχήν. ὅταν μὲν οὖν ἐν αὐτῷ τῷ κάτω τόπῳ ἡ ἀρχὴ τῆς συστάσεως ᾖ, καθ' ἑαυτὸν φαίνεται κομήτης 70 We have seen that when a fiery principle of this kind moves we seem to have a shooting-star: similarly when it stands still we seem to have a star standing still. We may compare these phenomena to a heap or mass of chaff into which a torch is thrust, or a spark thrown. That is what a shooting-star is like. The fuel is so inflammable that the fire runs through it quickly in a line. Now if this fire were to persist instead of running through the fuel and perishing away, its course through the fuel would stop at the point where the latter was densest, and then the whole might begin to move. Such is a comet-like a shooting-star that contains its beginning and end in itself. When the matter begins to gather in the lower region independently the comet appears by itself.
ὅταν δ' ὑπὸ τῶν ἄστρων τινός, ἢ τῶν ἀπλανῶν ἢ τῶν πλανήτων, ὑπὸ τῆς κινήσεως συνιστῆται ἡ (344b.) ἀναθυμίασις, τότε κομήτης γίγνεται τούτων τις οὐ γὰρ πρὸς αὐτοῖς ἡ κόμη γίγνεται τοῖς ἄστροις, ἀλλ' ὥσπερ αἱ ἅλῳ περὶ τὸν ἥλιον φαίνονται καὶ τὴν σελήνην παρακολουθοῦσαι, καίπερ μεθισταμένων, ὅταν οὕτως ᾖ πεπυκνωμένος ὁ ἀὴρ ὥστε τοῦτο γίγνεσθαι τὸ πάθος ὑπὸ τὴν τοῦ ἡλίου πορείαν, οὕτω καὶ ἡ κόμη τοῖς ἄστροις οἷον ἅλως ἐστίν πλὴν ἡ μὲν γίγνεται δι' ἀνάκλασιν τοιαύτη τὴν χρόαν, ἐκεῖ δ' ἐπ' αὐτῶν τὸ χρῶμα φαινόμενόν ἐστιν. 71 But when the exhalation is constituted by one of the fixed stars or the planets, owing to their motion, one of them becomes a comet. The fringe is not close to the stars themselves. Just as haloes appear to follow the sun and the moon as they move, and encircle them, when the air is dense enough for them to form along under the sun's course, so too the fringe. It stands in the relation of a halo to the stars, except that the colour of the halo is due to reflection, whereas in the case of comets the colour is something that appears actually on them.
ὅταν μὲν οὖν κατ' ἀστέρα γένηται ἡ τοιαύτη σύγκρισις, τὴν αὐτὴν ἀνάγκη φαίνεσθαι φορὰν κινούμενον τὸν κομήτην ἥνπερ φέρεται ὁ ἀστήρ ὅταν δὲ συστῇ καθ' αὑτόν, τότε ὑπολειπόμενοι φαίνονται. τοιαύτη γὰρ ἡ φορὰ τοῦ κόσμου τοῦ περὶ τὴν γῆν. τοῦτο γὰρ μάλιστα μηνύει μὴ εἶναι ἀνάκλασίν τινα τὸν κομήτην, ὡς ἅλω ἐν ὑπεκκαύματι καθαρῷ πρὸς αὐτὸν τὸν ἀστέρα γιγνομένην, καὶ μὴ ὡς λέγουσιν οἱ περὶ Ἱπποκράτην, πρὸς τὸν ἥλιον, ὅτι καὶ καθ' αὑτὸν γίγνεται κομήτης πολλάκις καὶ πλεονάκις ἢ περὶ τῶν ὡρισμένων τινὰς ἀστέρων. περὶ μὲν οὖν τῆς ἅλω τὴν αἰτίαν ὕστερον ἐροῦμεν 72 Now when this matter gathers in relation to a star the comet necessarily appears to follow the same course as the star. But when the comet is formed independently it falls behind the motion of the universe, like the rest of the terrestrial world. It is this fact, that a comet often forms independently, indeed oftener than round one of the regular stars, that makes it impossible to maintain that a comet is a sort of reflection, not indeed, as Hippocrates and his school say, to the sun, but to the very star it is alleged to accompany—in fact, a kind of halo in the pure fuel of fire. As for the halo we shall explain its cause later.
περὶ δὲ τοῦ πυρώδη τὴν σύστασιν αὐτῶν εἶναι τεκμήριον χρὴ νομίζειν ὅτι σημαίνουσι γιγνόμενοι πλείους πνεύματα καὶ αὐχμούς δῆλον γὰρ ὅτι γίγνονται διὰ τὸ πολλὴν εἶναι τὴν τοιαύτην ἔκκρισιν, ὥστε ξηρότερον ἀναγκαῖον εἶναι τὸν ἀέρα, καὶ διακρίνεσθαι καὶ διαλύεσθαι τὸ διατμίζον ὑγρὸν ὑπὸ τοῦ πλήθους τῆς θερμῆς ἀναθυμιάσεως, ὥστε μὴ συνίστασθαι ῥᾳδίως εἰς ὕδωρ. σαφέστερον δ' ἐροῦμεν καὶ περὶ τούτου τοῦ πάθους, ὅταν καὶ περὶ πνευμάτων λέγειν ᾖ καιρός. ὅταν μὲν οὖν πυκνοὶ καὶ πλείους φαίνωνται, καθάπερ λέγομεν, ξηροὶ καὶ πνευματώδεις γίγνονται οἱ ἐνιαυτοὶ ἐπιδήλως ὅταν δὲ σπανιώτεροι καὶ ἀμαυρότεροι τὸ μέγεθος, ὁμοίως μὲν οὐ γίγνεται τὸ τοιοῦτον, οὐ μὴν ἀλλ' ὡς ἐπὶ τὸ πολὺ γίγνεταί τις ὑπερβολὴ πνεύματος ἢ κατὰ χρόνον ἢ κατὰ μέγεθος, ἐπεὶ καὶ ὅτε ὁ ἐν Αἰγὸς ποταμοῖς ἔπεσε λίθος ἐκ τοῦ ἀέρος, ὑπὸ πνεύματος ἀρθεὶς ἐξέπεσε μεθ' ἡμέραν ἔτυχε δὲ καὶ τότε κομήτης ἀστὴρ γενόμενος ἀφ' ἑσπέρας. καὶ περὶ τὸν μέγαν ἀστέρα τὸν κομήτην ξηρὸς ἦν ὁ χειμὼν καὶ βόρειος, καὶ τὸ κῦμα δι' ἐναντίωσιν ἐγένετο πνευμάτων ἐν μὲν γὰρ τῷ κόλπῳ (345a.) βορέας κατεῖχεν, ἔξω δὲ νότος ἔπνευσε μέγας. ἔτι δ' ἐπ' ἄρχοντος Νικομάχου ἐγένετο ὀλίγας ἡμέρας κομήτης περὶ τὸν ἰσημερινὸν κύκλον, οὐκ ἀφ' ἑσπέρας ποιησάμενος τὴν ἀνατολήν, ἐφ' ᾧ τὸ περὶ Κόρινθον πνεῦμα γενέσθαι συνέπεσεν. 73 The fact that comets when frequent foreshadow wind and drought must be taken as an indication of their fiery constitution. For their origin is plainly due to the plentiful supply of that secretion. Hence the air is necessarily drier and the moist evaporation is so dissolved and dissipated by the quantity of the hot exhalation as not readily to condense into water. But this phenomenon too shall be explained more clearly later when the time comes to speak of the winds.—So when there are many comets and they are dense, it is as we say, and the years are clearly dry and windy. When they are fewer and fainter this effect does not appear in the same degree, though as a rule the is found to be excessive either in duration or strength. For instance when the stone at Aegospotami fell out of the air—it had been carried up by a wind and fell down in the daytime—then too a comet happened to have appeared in the west. And at the time of the great comet the winter was dry and north winds prevailed, and the wave was due to an opposition of winds. For in the gulf a north wind blew and outside it a violent south wind. Again in the archonship of Nicomachus a comet appeared for a few days about the equinoctial circle (this one had not risen in the west), and simultaneously with it there happened the storm at Corinth.
τοῦ δὲ μὴ γίγνεσθαι πολλοὺς μηδὲ πολλάκις κομήτας, καὶ μᾶλλον ἐκτὸς τῶν τροπικῶν ἢ ἐντός, αἴτιος ἡ τοῦ ἡλίου καὶ ἡ τῶν ἀστέρων κίνησις, οὐ μόνον ἐκκρίνουσα τὸ θερμόν, ἀλλὰ καὶ διακρίνουσα τὸ συνιστάμενον. μάλιστα δ' αἴτιον ὅτι τὸ πλεῖστον εἰς τὴν τοῦ γάλακτος ἀθροίζεται χώραν. 74 That there are few comets and that they appear rarely and outside the tropic circles more than within them is due to the motion of the sun and the stars. For this motion does not only cause the hot principle to be secreted but also dissolves it when it is gathering. But the chief reason is that most of this stuff collects in the region of the milky way.
Postquam philosophus reprobavit opiniones aliorum, hic incipit ponere opinionem propriam de cometis. 68. After refuting the opinions of others, the Philosopher here begins to give his own opinion on comets.
Et primo ostendit modum certitudinis qui est in hac materia exquirendus. Et dicit quod de talibus, quae sunt immanifesta sensui, non est exquirenda certa demonstratio et necessaria, sicut in mathematicis et in his quae subiacent sensui; sed sufficit per rationem demonstrare et ostendere causam, ita quod quaestionem solvamus per aliquam solutionem possibilem, ex qua non sequatur aliquod inconveniens, per ea quae hic apparent secundum sensum. Unde hoc modo in proposito ad habendam causam est procedendum. First, he explains the type of certitude to be sought in this matter [67] and says that with respect to such things, not accessible to sense observation, one must not look for a certain and necessary demonstration, as found in mathematics and in phenomena accessible to sense. It is enough to demonstrate with an argument and present a cause, in such a way as to solve the problem with some possible solution from which nothing impossible follows, according to what here appears to sense. Accordingly, this is the method to be employed in the present case to obtain a cause.
Secundo ibi: supponitur enim nobis etc., secundum praedictum modum incipit assignare causam de apparitione cometae. Et circa hoc duo facit: 69. Secondly, according to the aforesaid method he begins to assign a cause of the appearance of comets. About this he does two things:

primo assignat causam de apparitione cometae;

secundo de loco et tempore apparitionis, ibi: eius autem quod est et cetera.

First, he assigns the cause of the appearance of comets, at 70;

Secondly, of the place and time of their appearance, at 76.

Prima dividitur in duas: The first is divided into two parts:

in prima assignat causam apparitionis cometae;

secundo hoc manifestat per signum, ibi: de eo autem quod est et cetera.

In the first he gives the cause of the appearance of a comet, at 70;

Secondly, he manifests this through a sign, at 75.

Circa primum duo facit: Regarding the first he does two things:

primo ostendit cometas apparere ex duabus causis;

secundo ostendit differentiam inter cometas ex diversis causis apparentes, ibi: quando quidem igitur et cetera.

First, he shows that there are two causes of comets appearing, at 70;

Secondly, he shows the differences between comets that arise from diverse causes, at 74.

Circa primum tria facit. Primo resumit quaedam superius dicta, ad manifestandum propositum. Et dicit quod oportet supponere supradicta, quod huius inferioris mundi qui est circa terram, prima pars et suprema, sub corporibus circulariter motis, est exhalatio calidi et sicci. Iterum oportet supradicta supponere, quod ista exhalatio calida et sicca, et multa pars aeris, qui continuatur ad ignem, simul circumducitur circa terram sub sphaera caelesti, motu circulari, quasi delata et tracta a circulatione caeli. Et tertio oportet supponere quod exhalatio praedicta sic mota, frequenter ignitur, quocumque modo sit disposita ad hoc quod ignis in ea bene dominetur: propter quam causam fiunt discursus siderum, ut dictum est. 70. About the first he does three things: First [68], in order to manifest his proposition he re-introduces certain things already stated. And he says that we must maintain what has been said above to the effect that in the region of the lower world surrounding the earth, the first and highest part, below the bodies in circular motion, is the exhalation of the hot and dry. We must also suppose, as stated above, that this hot-dry exhalation, as well as a large portion of the air continuous with the fire, are revolved together around the earth, under the heavenly sphere, with a circular motion, as though carried and drawn along by the turning of the heaven. Thirdly, we must assume that the above-mentioned exhalation, thus moved, is frequently ignited in whatever way it happens to be disposed to allow fire to prevail well in it: this being, as was said, the cause of the shooing of certain stars.
Secundo ibi: cum igitur in talem etc., assignat causam apparitionis cometae. Et dicit quod quando talis exhalatio fuerit condensata, et propter motum superioris corporis inciderit in ipsam exhalationem aliquod principium igneum, ita scilicet quod ex aliqua parte incipiat exuri; sic quod ignis non sit tam multus ut cito exurat materiam, neque etiam sit ita debilis ut cito extinguatur priusquam accendatur, sed sit talis quod plus et diu possit permanere, cum quantitate ignis et dispositione materiae inspissatae; cum hoc etiam quod simul de inferioribus ascendat continue exhalatio bene disposita ad hunc modum exustionis, ut scilicet diu duret; tunc fit stella cometa: quia illud quod iam ignitum est videtur quasi stella, reliqua autem exhalatio, quae nondum est perfecte ignita, sed apta ignitioni, videtur coma eius. Quia qualitercumque figuretur talis exhalatio, huiusmodi figura videbitur. Quia si exhalatio sit undique circumposita stellae, idest principio vel parti ignitae, videtur quasi coma, unde et cometes dicitur: si autem disponatur ad longitudinem principii igniti, videtur exhalatio esse quasi barba stellae, et ideo vocatur pogonias, idest quasi barbatus. 71. Secondly [69], he assigns a cause for the appearance of a comet and says that when such an exhalation condenses and when, as a result of the higher body's-motion, a source of combustion falls into this exhalation and causes a flame to burst out in a certain area in such a way that the fire is neither large enough to consume all the material quickly, nor so weak as to quickly die out before a conflagration occurs, but such as to last more and for a long time, in keeping with the size of the fire and the disposition of the condensed matter; and when along with this there continually rises from below an exhalation well disposed for this type of burning, i.e., sufficient to keep it burning for a long time, then it is that comets are formed. — For the material already on fire appears to be a star, while the rest of the exhalation, which is not yet completely ignited but on the way to being ignited appears as a tail. The shape of the exhalation determines the shape that will appear: if the exhalation completely surrounds the "star," i.e., the origin or ignited part, there appears, as it were, a circle of tresses [coma], hence it is called "cometed"; but if it is disposed along the length of the ignited origin, then the exhalation appears as though the beard of the star, and is therefore said to be "pogoniated," i.e., bearded.
Tertio ibi: sicut autem talis latio etc., manifestat quod dictum est de cometa, per comparationem ad stellam cadentem. Dictum est enim supra quod motus ignis accensi in tali materia, cum fuerit motus per expulsionem, videtur esse motus stellae: et similiter mansio vel quies igniti principii in praedicta materia, videtur esse mansio vel quies stellae. Dicit autem stellam cometam quiescere, ad excludendum motum qui apparet in stellis cadentibus; non autem ad excludendum motum cometae secundum quod circumvolvitur simul cum caelo, de quo post dicet. Huiusmodi autem mansio praedicti principii accidit propter hoc, quod materia non statim consumitur; tum propter multitudinem et spissitudinem, et ignis debilitatem; tum propter aliam materiam succedentem, ut dictum est. 72. Thirdly [70], he explains what was said about a comet by comparison with a falling star. For it was said above that the motion of fire ignited in such material, when it is moved by ejection, seems to be the motion of a star; similarly, the tarrying or state of rest of the fiery principle in this matter seems to be the tarrying or state of rest of a star. He says that a comet star is at rest so as to exclude the motion which appears in falling stars, but not so as to exclude the comet's motion as it is revolved along with the heaven. He will speak of this later. The reason why the above-mentioned principle tarries is that the material is not consumed at once, owing to the amount and thickness of the material and to the weakness of the fire, as well as to the other material that replaces it, as has been said.
Et est simile sicut si aliquis in magnum cumulum palearum immiserit titionem, aut aliud quodcumque ignitum principium: non enim statim discurret, quasi exurens paleam, sed videtur ignitio diu in uno loco manere. Et ita, si quis recte consideret, videtur similitudinem quandam habere discursus stellarum cadentium apparitioni cometae. Quia in stellis discurrentibus cito procedit ignitio in longitudinem, propter dispositionem scilicet hypeccaumatis ad hoc quod de facili aduratur: sed si ignitio maneret, et non pertransiret consumendo materiam, aut materia esset multum densa, ut non posset cito consumi, tunc, quasi subtracto medio discursu, remaneret solummodo stella manens, sicut est in principio discursus et in termino. It is as though someone threw a torch or other burning source into a large pile of chaff: the fire does not at once travel as though consuming the chaff, but the igniting seems to remain in one area for a long time. From this example properly understood one can see that the shooting of falling stars has a certain likeness to the appearance of a comet. For in shooting stars the fire travels quickly along the length on account of the disposition, namely, in the fuel, that permits it to be easily burned; but if the flame were to tarry and not pass along by consuming the matter, or if the material were very dense, so as not to be swiftly consumed, then, as though the intermediate trajectory had been taken away, there would only be the star standing, as is the case in the beginning and end of the trajectory.
Et tale quid est cometa: ut imaginemur quod cometa sit quasi stella discurrens, prout talis stella est in principio et in fine discursus, subtracto motu discursionis. Sic igitur concludit quod, quando principium consistentiae ipsius fuerit in inferiori loco, idest sub globo lunari, dicitur cometa per se apparens, sine aliqua stella errante vel fixa. Such is the comet. Thus we can imagine a comet as though it were a shooting star, as such a star is at the beginning and end of its course but with no shooting motion. He therefore concludes that when the source of its consistency was "in a lower place," i.e., under the lunar globe, a comet is said to appear by itself, without being accompanied by any star, either wandering or fixed.
Deinde cum dicit: quando autem sub astrorum aliquo etc., assignat alium modum apparitionis cometae. Et dicit quod quando sub aliqua stellarum errantium vel non errantium, exhalatio adunatur per motum illius stellae, tunc aliqua stellarum dictarum fit cometa: non quod stella quae apparet sit aliquod igneum in aere, sicut in superiori modo dictum est, sed est verax stella, errans vel non errans; non tamen coma eius fit in loco caelesti ubi sunt astra, sed est sub caelo in aere. 73. Then [71] he describes another way in which comets appear. And he says that when an exhalation is collected under some star, wandering or not wandering, on account of the motion of that star, then some such star becomes a comet — not that the star which appears is a fiery object in the air, as in the case cited above, but it is a true star, wandering or not wandering. Its "coma," however, does not come into existence in the heavenly region where the stars are, but under the heaven in the air.
Et ponit exemplum de halo, idest de aere qui videtur aliquando circumstare solem et lunam, etiam sole et luna motis. Huiusmodi enim halo non est in loco solis et lunae, licet sequatur solem et lunam, etiam sole et luna motis: haec enim passio fit in aere condensato sub motu solis et lunae, ut infra dicetur. Sicut igitur halo se habet ad solem et lunam, ita coma se habet ad stellas fixas vel erraticas, quando apparent cum comis: et est aliqua exhalatio inferius, scilicet in superiori loco aeris, consequens motum illarum stellarum. Sed tamen haec est differentia inter halo et comam, quia color eius quod dicitur halo, non est in ipso vapore, sed est ex reverberatione ad nubem, ut infra ostendetur: sed hoc quod videtur de comis, est proprie color ipsarum exhalationum fumosarum. And he gives the example of the "halo," i.e., of the air which sometimes is seen to surround the sun and moon, even though the sun and moon are in motion. Such a halo does not exist in the place where the sun and moon exist, though it accompany the sun and moon, even when the latter are moved. This passion comes into existence in the air condensed under the course of the sun and moon, as will be explained later. Therefore, just as a halo is to the sun and moon, so a "coma" is to the fixed stars and wanderers, whenever they appear with a "coma," which is a certain exhalation farther down, namely, in the upper region of the air, deriving from the motion of those stars. Yet there is this difference between a halo and a "coma": the color of a halo is not in the vapor itself but is something that results from reflection toward a cloud, as will be explained later; but the color associated with a "coma" is properly a color belonging to the fumid exhalations themselves.
Deinde cum dicit: quando quidem igitur etc., ostendit differentiam inter cometas secundum duos dictos modos apparentes. Et dicit quod quando adunatio exhalationis fit secundum aliquam stellam fixam vel errantem, necesse est quod in cometa manifeste videatur ille motus qui est stellae cui adhaeret coma: sed quando stella cometa est per se ignis existens in aere, sine aliqua superiorum stellarum, tunc videntur subtardantes. 74. Then at [72] he points out the difference between comets as appearing in these two ways. And he says that when the accumulation of an exhalation takes place in relation to a fixed or wandering star, it is necessary that there clearly appear in the comet the motion which belongs to the star to which the "coma" belongs; but when the comet star is fire existing per se in the air without any of the upper stars, then they seem to lag.
Et hoc manifestat per hoc quod latio inferioris mundi qui est circa terram, talis est, scilicet tardior motu caelesti: quamvis enim circumvolvatur ignis et magna pars aeris per motum firmamenti, non potest tamen attingere ad velocitatem motus caelestis. Exhalatio igitur ignita existens in superiori parte aeris, circumvolvitur solum cum aere et igne: sed quia motus horum corporum est tardior motu firmamenti, ideo cometa existens in aere remanet post corpora caelestia, quae velocissime moventur; et sic videtur habere motum contrarium firmamento, sicut et planetae, ex sola retardatione. Quod etiam quidam opinati sunt circa planetas: et inde est etiam quod praedictae opiniones posuerunt cometas esse planetas. He explains this by the fact that the course of the lower world about the earth is such, namely, slower than the heavenly movement — for although fire and a large portion of the air are revolved by the motion of the firmament, they nevertheless cannot attain to the speed of the heavenly motion. Therefore the burning exhalation existing in the upper region of air is revolved along with the air and the fire. Because their motion is slower than that of the firmament, therefore the comet existing in the air remains behind the heavenly bodies, which are moving most rapidly. Consequently, from its slowness alone, it seems to have a movement contrary to the firmament, just as the planets do. Some indeed thought this of the planets — hence the aforesaid opinions posited that comets are planets.
Sed hoc quod cometa saepe fit per se, et frequentius quam circa aliquam stellarum determinatarum, idest fixarum, quae habent esse fixum et determinatum in caelo, maxime manifestat quod cometa non est repercussio facta in exhalatione (quam nominat hypeccauma) ad ipsam stellam cui adhaeret coma, sicut est in halo. Si autem esset sicut est in halo, fieret repercussio visus ab exhalatione ad ipsam stellam, et non ad solem, sicut dicunt sequaces Hippocratis. Sed de halo posterius dicetur. But the very fact that a comet is often produced by itself, and this more frequently than in association with any of the "determinate," i.e., fixed, stars which have a fixed and determinate existence in the heaven, shows most plainly that a comet is not a reflexion produced in the exhalation (which he calls "hypeccauma" [fuel]) to the star to which the "coma" is attached, as is the case with a halo. But if it were as it is with a halo, the reflection of our vision would pass from the exhalation to the star, and not to the sun, as the followers of Hippocrates claim. But an account of the halo will be given later.
Deinde cum dicit: de eo autem quod est etc., manifestat quod dixerat, per signum. Et dicit quod huius quod est consistentiam cometarum esse igneam, vel quantum ad comam apparentem, argumentum est hoc, quod plures cometae significant spiritus et siccitates. Manifestum est enim quod venti et siccitates fiunt propter hoc, quod multa exhalatio sicca est segregata a terra; unde necesse est aerem esse sicciorem, et humidum quod evaporat ab aquis, rarefieri et dissolvi, propter multitudinem calidae exhalationis, ita quod non de facili vapores in aquam condensentur, sed magis generentur venti, qui causantur ex exhalationibus siccis; hoc autem erit manifestius quando dicetur de ventis. Sic igitur, quando apparent frequentes et multi cometae, quod accidit propter multitudinem exhalationis siccae, oportet quod anni sint notabiliter sicci et ventosi. Sed quando rarius fiunt cometae, et non ita magni fiunt, non sunt anni notabiliter sicci et ventosi; sed tamen, ut frequenter, fit excessus venti, aut secundum tempus, quia diu durat, aut secundum magnitudinem, quia vehementer flat. 75. Then [73] he manifests what he had said, through a sign. And he says that an argument to show that the stuff of comets is fiery, or so far as the fringe [coma] appears, is that a number of comets is a herald of winds and droughts. For it is plain that winds and droughts are the result of much dry exhalation being drawn from the earth; as a result, the air is quite dry and the moisture which evaporates from the seas is rarified and dissolved by the abundance of hot exhalation; consequently, vapors are not easily condensed into water; rather, winds caused from the dry exhalations are generated. This will become clearer when winds are discussed. Thus, therefore, when frequent and numerous comets appear, which occurs as a result of the abundance of dry exhalation, the years are necessarily unusually dry and windy. But when the comets are less frequent, and not so large, the years are not notably dry and windy; yet frequently there is an excess of wind, either in duration because they last long, or in strength, because they blow furiously.
Et ponit exempla. Aliquando enim in quibusdam fluviis cecidit lapis ex aere per diem, elevatus a vento; et tunc fuit factus quidam cometa circa vesperum. Et similiter circa illum magnum cometam de quo supra dixit, fuit hiems sicca et borealis, et propter contrarietatem ventorum factus fuit superexcessus fluctuum, ita quod propter hoc destructae dicuntur quaedam civitates; quia extra in pelago flabat magnus Auster, sed in sinu vincebat Boreas. Similiter sub principe Nicomacho apparuit quidam cometa, et tunc etiam fuit factus magnus ventus apud Corinthum. He gives examples. For sometimes a stone dropped into certain rivers from the air during the day, having been lifted by the wind; and then, that evening, a comet was formed. And the same is true of that large comet he referred to earlier: it was a dry winter with prevailing north winds, and because of contrary winds a tidal wave resulted and some cities are said to have been destroyed — for out on the sea a strong south wind was blowing, but in the bay a north wind prevailed. Likewise, under the rule of Nicomachus, a certain comet appeared and then a strong wind blew up in Corinth.
Deinde cum dicit: eius autem quod est etc., assignat causam de loco et tempore apparitionis cometae. Et dicit quod causa eius quod non fiant multi neque saepe, et magis extra tropicos, idest extra viam solis, quam intra, est quod per motum solis et astrorum non solum sunt exhalationes calidae a terra resolutae, sed etiam, si aliquid est in huiusmodi exhalationibus consistens et spissum, per motum solis et stellarum disgregatur; et sic impeditur causa apparitionis cometae, nisi quando fuerit superabundans talis exhalationis multiplicatio, quod raro accidit. Et maxime etiam causa est rarae apparitionis cometarum, quia plurimum de materia tali ex qua causatur apparitio cometae, adunatur in regione lactei circuli, ut infra dicetur: unde raro tantum multiplicatur exhalatio, quod sufficiat apparitioni cometae et lactei circuli. 76. Then [74] he assigns the cause for the place and time of a comet's appearance. And he says that the reason why comets are few and infrequent and occur more often outside the "tropics," i.e., outside the sun's path, than within, is that the motion of the sun and stars not only releases the hot exhalations resolved from the earth, but also breaks up any consistency and thickness that might be in them. In this way the cause of a comet's appearing is hindered except in cases when there is a superabundant accumulation of such exhalations, which happens rarely. The main reason why comets appear rarely is that most of the matter which causes the appearance of comets is accumulated in the region of the milky circle, as will be said later: hence it is rarely that enough exhalation accumulates to account for the appearance both of a comet and of the "milky circle."

Lecture 12
Opinions of others on the Milky Way
Chapter 8
ὅπως δὲ καὶ διὰ τίν' αἰτίαν γίγνεται καὶ τί ἐστι τὸ γάλα, λέγωμεν ἤδη. προδιέλθωμεν δὲ καὶ περὶ τούτου τὰ παρὰ τῶν ἄλλων εἰρημένα πρῶτον. 75 Let us now explain the origin, cause, and nature of the milky way. And here too let us begin by discussing the statements of others on the subject.
τῶν μὲν οὖν καλουμένων Πυθαγορείων φασί τινες ὁδὸν εἶναι ταύτην οἱ μὲν τῶν ἐκπεσόντων τινὸς ἀστέρων, κατὰ τὴν λεγομένην ἐπὶ Φαέθοντος φθοράν, οἱ δὲ τὸν ἥλιον τοῦτον τὸν κύκλον φέρεσθαί ποτέ φασιν οἷον οὖν διακεκαῦσθαι τὸν τόπον τοῦτον ἤ τι τοιοῦτον ἄλλο πεπονθέναι πάθος ὑπὸ τῆς φορᾶς αὐτῶν. 76 (1) Of the so-called Pythagoreans some say that this is the path of one of the stars that fell from heaven at the time of Phaethon's downfall. Others say that the sun used once to move in this circle and that this region was scorched or met with some other affection of this kind, because of the sun and its motion.
ἄτοπον δὲ τὸ μὴ συννοεῖν ὅτι εἴπερ τοῦτ' ἦν τὸ αἴτιον, ἔδει καὶ τὸν τῶν ζῳδίων κύκλον οὕτως ἔχειν, καὶ μᾶλλον ἢ τὸν τοῦ γάλακτος ἅπαντα γὰρ ἐν αὐτῷ φέρεται τὰ πλανώμενα καὶ οὐχ ὁ ἥλιος μόνος. δῆλος δ' ἡμῖν ἅπας ὁ κύκλος αἰεὶ γὰρ αὐτοῦ φανερὸν ἡμικύκλιον τῆς νυκτός. ἀλλὰ πεπονθὼς οὐδὲν φαίνεται τοιοῦτον, πλὴν εἴ τι συνάπτει μόριον αὐτοῦ πρὸς τὸν τοῦ γάλακτος κύκλον. 77 But it is absurd not to see that if this were the reason the circle of the Zodiac ought to be affected in the same way, and indeed more so than that of the milky way, since not the sun only but all the planets move in it. We can see the whole of this circle (half of it being visible at any time of the night), but it shows no signs of any such affection except where a part of it touches the circle of the milky way.
οἱ δὲ περὶ Ἀναξαγόραν καὶ Δημόκριτον φῶς εἶναι τὸ γάλα λέγουσιν ἄστρων τινῶν τὸν γὰρ ἥλιον ὑπὸ τὴν γῆν φερόμενον οὐχ ὁρᾶν ἔνια τῶν ἄστρων. ὅσα μὲν οὖν περιορᾶται ὑπ' αὐτοῦ, τούτων μὲν οὐ φαίνεσθαι τὸ φῶς (κωλύεσθαι γὰρ ὑπὸ τῶν τοῦ ἡλίου ἀκτίνων) ὅσοις δ' ἀντιφράττει ἡ γῆ ὥστε μὴ ὁρᾶσθαι ὑπὸ τοῦ ἡλίου, τὸ τούτων οἰκεῖον φῶς εἶναί φασι τὸ γάλα. φανερὸν δ' ὅτι καὶ τοῦτ' ἀδύνατον τὸ μὲν γὰρ γάλα ἀεὶ τὸ αὐτὸ ἐν τοῖς αὐτοῖς ἐστιν ἄστροις (φαίνεται γὰρ μέγιστος ὢν κύκλος), 78 (2) Anaxagoras, Democritus, and their schools say that the milky way is the light of certain stars. For, they say, when the sun passes below the earth some of the stars are hidden from it. Now the light of those on which the sun shines is invisible, being obscured by the of the sun. But the milky way is the peculiar light of those stars which are shaded by the earth from the sun's rays.
ὑπὸ δὲ τοῦ ἡλίου ἀεὶ ἕτερα τὰ οὐχ ὁρώμενα διὰ τὸ μὴ ἐν ταὐτῷ μένειν τόπῳ. ἔδει οὖν μεθισταμένου τοῦ ἡλίου μεθίστασθαι καὶ τὸ γάλα νῦν δὲ οὐ φαίνεται τοῦτο γιγνόμενον. 79 This, too, is obviously impossible. The milky way is always unchanged and among the same constellations (for it is clearly a greatest circle), whereas, since the sun does not remain in the same place, what is hidden from it differs at different times. Consequently with the change of the sun's position the milky way ought to change its position too: but we find that this does not happen.
πρὸς (345b.) δὲ τούτοις, εἰ καθάπερ δείκνυται νῦν ἐν τοῖς περὶ ἀστρολογίαν θεωρήμασιν, τὸ τοῦ ἡλίου μέγεθος μεῖζόν ἐστιν ἢ τὸ τῆς γῆς καὶ τὸ διάστημα πολλαπλασίως μεῖζον τὸ τῶν ἄστρων πρὸς τὴν γῆν ἢ τὸ τοῦ ἡλίου, καθάπερ τὸ τοῦ ἡλίου πρὸς τὴν γῆν ἢ τὸ τῆς σελήνης, οὐκ ἂν πόρρω που τῆς γῆς ὁ κῶνος ὁ ἀπὸ τοῦ ἡλίου συμβάλλοι τὰς ἀκτῖνας, οὐδ' ἂν ἡ σκιὰ πρὸς τοῖς ἄστροις εἴη τῆς γῆς, ἡ καλουμένη νύξ ἀλλ' ἀνάγκη πάντα τὸν ἥλιον τὰ ἄστρα περιορᾶν, καὶ μηδενὶ τὴν γῆν ἀντιφράττειν αὐτῶν. 80 Besides, if astronomical demonstrations are correct and the size of the sun is greater than that of the earth and the distance of the stars from the earth many times greater than that of the sun (just as the sun is further from the earth than the moon), then the cone made by the rays of the sun would terminate at no great distance from the earth, and the shadow of the earth (what we call night) would not reach the stars. On the contrary, the sun shines on all the stars and the earth screens none of them.
ἔτι δ' ἐστὶν τρίτη τις ὑπόληψις περὶ αὐτοῦ λέγουσιν γάρ τινες ἀνάκλασιν εἶναι τὸ γάλα τῆς ἡμετέρας ὄψεως πρὸς τὸν ἥλιον, ὥσπερ καὶ τὸν ἀστέρα τὸν κομήτην. 81 (3) There is a third theory about the milky way. Some say that it is a reflection of our sight to the sun, just as they say that the comet is.
ἀδύνατον δὲ καὶ τοῦτο εἰ μὲν γὰρ τό τε ὁρῶν ἠρεμοίη καὶ τὸ ἔνοπτρον καὶ τὸ ὁρώμενον ἅπαν, ἐν τῷ αὐτῷ σημείῳ τοῦ ἐνόπτρου τὸ αὐτὸ φαίνοιτ' ἂν μέρος τῆς ἐμφάσεως εἰ δὲ κινοῖτο τὸ ἔνοπτρον καὶ τὸ ὁρώμενον ἐν τῷ αὐτῷ μὲν ἀποστήματι πρὸς τὸ ὁρῶν καὶ ἠρεμοῦν, πρὸς ἄλληλα δὲ μήτε ἰσοταχῶς μηδ' ἐν τῷ αὐτῷ ἀεὶ διαστήματι, ἀδύνατον τὴν αὐτὴν ἔμφασιν ἐπὶ τοῦ αὐτοῦ εἶναι μέρους τοῦ ἐνόπτρου. τὰ δ' ἐν τῷ τοῦ γάλακτος κύκλῳ φερόμενα ἄστρα κινεῖται καὶ ὁ ἥλιος πρὸς ὃν ἡ ἀνάκλασις, μενόντων ἡμῶν, καὶ ὁμοίως καὶ ἴσον πρὸς ἡμᾶς ἀπέχοντα, αὐτῶν δ' οὐκ ἴσον ὁτὲ μὲν γὰρ μέσων νυκτῶν ὁ δελφὶς ἐπιτέλλει, ὁτὲ δὲ ἕωθεν, τὰ δὲ μόρια τοῦ γάλακτος τὰ αὐτὰ μένει ἐν ἑκάστῳ. καίτοι οὐκ ἔδει, εἰ ἦν ἔμφασις, ἀλλὰ μὴ ἐν αὐτοῖς τι ἦν τοῦτο τὸ πάθος τοῖς τόποις. 82 But this too is impossible. For if the eye and the mirror and the whole of the object were severally at rest, then the same part of the image would appear at the same point in the mirror. But if the mirror and the object move, keeping the same distance from the eye which is at rest, but at different rates of speed and so not always at the same interval from one another, then it is impossible for the same image always to appear in the same part of the mirror. Now the constellations included in the circle of the milky way move; and so does the sun, the object to which our sight is reflected; but we stand still. And the distance of those two from us is constant and uniform, but their distance from one another varies. For the Dolphin sometimes rises at midnight, sometimes in the morning. But in each case the same parts of the milky way are found near it. But if it were a reflection and not a genuine affection of these this ought not to be the case.
ἔτι δὲ νύκτωρ ἐν ὕδατι καὶ τοῖς τοιούτοις ἐνόπτροις τὸ μὲν γάλα ἐμφαίνεται θεωροῦσι, τὸ δὲ τὴν ὄψιν ἀνακλᾶσθαι πρὸς τὸν ἥλιον πῶς δυνατόν; 83 Again, we can see the milky way reflected at night in water and similar mirrors. But under these circumstances it is impossible for our sight to be reflected to the sun.
ὅτι μὲν οὖν οὔτε ὁδὸς τῶν πλανήτων οὐδενὸς οὔτε φῶς ἐστι τῶν μὴ ὁρωμένων ἄστρων οὔτ' ἀνάκλασις, ἐκ τούτων φανερόν. σχεδὸν δὲ ταῦτ' ἐστὶν μόνον τὰ μέχρι τοῦ νῦν παραδεδομένα παρὰ τῶν ἄλλων 84 These considerations show that the milky way is not the path of one of the planets, nor the light of imperceptible stars, nor a reflection. And those are the chief theories handed down by others hitherto.
Postquam philosophus determinavit de stellis cadentibus et cometis, nunc determinat de lacteo circulo. 77. After determining concerning falling stars and comets, the Philosopher here determines concerning the milky circle.

Et primo ostendit de quo est intentio. Et dicit quod iam dicendum est de lacteo circulo, qualiter et propter quam causam est apparitio eius, et quid est illa claritas quae est quasi lac; hoc servato ordine, ut primo discutiamus ea quae ab aliis dicta sunt.

Secundo ibi: vocatorum quidem igitur etc., exequitur propositum.

First, he states his intention [75] and says that we must talk now of the milky circle: the how and why of its appearance and what that milky brightness is. But we shall adhere to that order whereby we first discuss what others have said;

Secondly, he executes his proposition, at 78.

Et primo ponit opiniones aliorum;

secundo opinionem propriam, ibi: nos autem dicamus et cetera.

First he presents the opinions of others, at 78;

Secondly, his own opinion (L. 13).

Prima dividitur in tres, secundum tres opiniones quas ponit:

secunda incipit ibi: qui autem circa Anaxagoram etc.;

tertia ibi: amplius autem est tertia et cetera.

The first is divided into three parts according to the three opinions he cited;

The second opinion begins at 80;

The third at 83.

Circa primum duo facit. Primo ponit opinionem. Et dicit quod quidam de numero philosophorum qui vocantur Pythagorici, dixerunt quod lacteus circulus est quaedam via. Sed in hoc diversificati sunt: quidam enim dixerunt quod erat via alicuius stellae quae per hanc partem caeli transivit, derelicto proprio cursu, tempore exorbitationis caeli, quae dicitur in fabulis fuisse facta sub Phaetonte; sed alii dicunt quod per istum circulum quandoque transivit sol. Et ita per motum solis vel stellae, locus iste caeli est quasi exustus, vel passus aliquam talem passionem, ut videatur ibi quaedam albedo. 78. Regarding the first he does two things. First, he presents the opinion at [76] and says that some of the philosophers called "Pythagoreans" held that the milky circle is a certain path. But their opinions differed: for some asserted that it was the path of a certain star that passed through this part of the heaven after abandoning its own course when the heavens once went off the path — an event which the fables declare happened under Phaethon. Others say that the sun once travelled that path. Consequently, by the motion of the sun or of a star that area of the heaven was, so to speak, scorched, or affected in such a way that a patch of whiteness now appears there.
Secundo ibi: inconveniens autem etc., improbat hanc opinionem. Et dicit quod inconveniens fuit quod ponentes hanc opinionem non simul intelligebant quod, si transitus solis vel stellae esset causa huius claritatis in hac parte caeli, multo magis oportebat quod haec dispositio esset in circulo zodiaco, quam in circulo lacteo: quia non solum sol, sed omnes stellae errantes feruntur per zodiacum. Circulus autem zodiacus totus manifestus est nobis, diversis temporibus, quia de nocte semper apparet medietas zodiaci super terram (terra enim obtinet vicem puncti respectu sphaerae stellarum fixarum: unde per grossitiem terrae nihil occultatur nobis de zodiaco): sed quamvis totus zodiacus sit a nobis visibilis, tamen non videtur in eo aliqua talis dispositio, nisi in parte qua coniungitur lacteo circulo. 79. Secondly [77], he rejects this opinion and says that it is an inconsistency for those who posited this opinion that they did not at the same time see that, if the journey of the sun or a star were the cause of this brightness in this region of the heaven, such a disposition has much more reason for appearing in the circle of the Zodiac than in the milky circle — for not only the sun, but all the wandering stars move through the Zodiac. Now the whole zodiacal circle is visible to us, at different times, because at night half of it always appears above the earth (for the earth has the status of a point compared to the sphere of the fixed stars: hence earth's largeness does not conceal anything in the Zodiac from us); but although the entire Zodiac is visible to us, no such disposition appears in it, save in the region where it is joined with the milky circle.
Deinde cum dicit: qui autem circa Anaxagoram etc., ponit secundam opinionem. Et primo recitat eam. Et dicit quod sectatores Anaxagorae et Democriti dixerunt claritatem lacteam quae apparet in caelo, esse lumen quarundam stellarum. Cum enim sol fertur sub terra, dicebant quod umbra terrae pertingit usque ad sphaeram stellarum fixarum, et occultat quasdam stellas, ne recipiant radios solis; non autem omnes, quia propter parvitatem terrae, umbra eius non occupat totum caelum, sed aliquam parvam partem. Dicebant enim quod claritas stellarum quae respiciuntur a sole, non apparet, quia prohibetur apparere a radiis solis ad eas pertingentibus; et sic circa eas non videtur claritas lactis. Sed illarum stellarum ad quas non pertingunt radii solis, impediente terra, apparet proprium lumen; quod dicebant esse claritatem lactis. 80. Then [78] he presents the second opinion. First, he recites it and says that the followers of Anaxagoras and Democritus declared that the milky brightness which appears in the heaven is the light of certain stars. For when the sun is borne below the earth, they said, the earth's shadow reaches as far as the sphere of the fixed stars and covers some of them so that they do not receive the sun's rays; yet it does not cover all of them, because, due to the smallness of the earth, its shadow does not cover the entire heaven but only a small area. For they said that the brightness of the stars faced by the sun does not appear, because it is prevented from appearing by the sun's rays reaching them; consequently, no milky brightness surrounds them. But of the stars which the sun's rays do not reach, because the earth prevents this, their own light appears, which they identify as the milky brightness.
Secundo ibi: manifestum est autem etc., reprobat hanc opinionem per duas rationes. Quarum primam ponit, dicens manifestum esse hoc quod dictum est esse impossibile. Quia claritas lactis semper apparet in eisdem stellis: quia circulus lacteus videtur esse unus de maximis circulis sphaerae, qui dividit eam per medium. Sed quia sol non semper manet in eodem loco caeli, oportet quod semper sint alia et alia astra quae occultantur radiis solis per umbram terrae: quia oportet imaginari motum umbrae in oppositum motui solis. Si igitur occultatio stellarum per umbram terrae esset causa apparitionis lacteae claritatis, oporteret, moto sole, transferri et lacteam claritatem. Sed hoc non videtur fieri, quia semper apparet in eodem loco et in eisdem stellis, ut dictum est. Falsa est igitur praedicta opinio. 81. Secondly [79], he rejects this opinion for two reasons. In presenting the first of them he says that what it claims is impossible. For the milky brightness always appears in the same stars — the milky circle being seen to be one of the largest circles, which divide the sphere in half. But because the sun does not always remain in the same place in the heaven, other and other stars must always be being obscured from the sun's rays by the earth's shadow — since the shadow's motion must be imagined as opposite to the sun's course. Therefore, if the cause of the milky brightness' visibility were the earth's shadow blotting out the stars, then as the sun moved, the milky brightness would also have to shift. But this is not seen to happen, because it always appears in the same place and in the same stars, as was said. Consequently, the aforesaid theory is false.
Secundam rationem ponit ibi: adhuc autem si quemadmodum etc., dicens quod probatum est per astrologicas rationes et considerationes, quod sol est maior terra, et quod plus distant astra fixa a terra quam sol, sicut et sol plus quam luna. Quando autem corpus lucidum est maius corpore opaco ex cuius oppositione fit umbra, umbra non ascendit in immensum, sed pyramidaliter ascendit in conum usque ad aliquam quantitatem; et tanto minorem, quanto corpus lucidum minus distat a corpore opaco, et quanto magis excedit ipsum. Unde manifestum est quod non multum longe conus umbrae terrae proiicitur ad radios qui sunt a sole, neque umbra terrae, quae vocatur nox, est apud astra fixa: sed necesse est quod sol prospiciat omnia astra fixa, et quod nulli eorum obsistat terra. Obsistit autem lunae eclipsans ipsam, quia est inferior sole, ut dictum est. Et sic patet quod praedicta opinio falsum supponebat. 82. He gives the second reason [80] and says that astronomical arguments and considerations prove that the sun is larger than earth and that the fixed stars are much farther from the earth than the sun is, just as the sun is farther from us than the moon is. Now when a shining body is larger than the opaque body whose interposition produces a shadow, the shadow does not increase indefinitely, rather it ascends in pyramid form to a cone of a certain quantity which is proportionately less as the shining body is less distant from the opaque one, and the more the former's size exceeds the latter's. Hence it is plain that the cone of the earth's shadow is not projected very far with respect to the rays coming from the sun; neither does the earth's shadow, which we call "night," reach as far as the fixed stars. What has to happen is that the sun has a view of all the fixed stars and that the earth blankets none of them. The reason why it blankets the moon and eclipses it is that the moon is lower than the sun, as has been said. Consequently, it is plain that the theory under discussion presupposed something false.
Tertiam opinionem ponit ibi: amplius autem est tertia et cetera. Et primo recitat ipsam, dicens quod quaedam tertia opinio fuit de circulo lacteo. Dixerunt enim quidam quod claritas lactea est ex eo quod visus noster repercutiebatur a stellis quibusdam ad solem; et ideo apparebat claritas circa illas stellas repercutientes visum, ita quod sunt quasi quoddam speculum claritatis solaris, sicut et Hippocrates dixit de apparitione cometae. 83. He presents the third opinion [81], and first he recites it, saying that there is a certain third theory about the milky circle. For some said that the milky brightness is due to our vision's being reflected from certain stars to the sun; as a result a brightness appeared around those stars striking our vision, so that they act as a certain mirror for the sun's brilliance, as Hippocrates also said when explaining the appearance of comets.
Secundo ibi: impossibile autem etc., improbat hanc opinionem per duas rationes. Quarum primam ponit, dicens quod impossibile est quod praedicta opinio ponit. Et praemittit hanc propositionem. Si omne, idest totum hoc, scilicet videns et speculum et res quae videtur per speculum, immobilis maneat, necesse est quod eadem pars emphaseos, idest formae apparentis, appareat in eodem signo speculi, idest in eodem puncto ad quod fit repercussio lineae visualis. Sed si speculum moveatur, et similiter res visa per speculum, videns autem quiescat; et illa duo quae moventur, semper remaneant in eadem distantia ad videntem, sed adinvicem comparata neque aequali velocitate moventur, neque sunt semper in eadem distantia; impossibile est quod eadem apparitio fiat in eadem parte speculi. Quia nihil differt quod speculum et res visa moveantur diversa velocitate, quam si unum moveretur et alterum quiesceret: quod si esset, manifestum est quod videretur in alia et alia parte speculi forma rei visae, propter diversam oppositionem secundum situm. Et hoc dico si videns quiescat: quia si videns moveatur, et speculum quiesceret, et res visa moveatur, posset forma rei visae apparere in eadem parte speculi; quia per motum videntis recompensaretur quod deesset motu rei visae, si sic proportionaliter moverentur. Unde oportet quod, quando videns quiescit, et speculum et res visa moventur inaequali velocitate, quod forma non appareat in eadem parte speculi. 84. Secondly [82], he rejects this theory for two reasons. He sets down the first of these and says that the above opinion posits something impossible. And he lays down this proposition: If "everything," i.e., the entire system, namely, the beholder, the mirror, and the object seen by means of the mirror, all remain at rest, then of necessity the same part of the "emphaseos," i.e., of the form appearing, will appear "on the same sign of the mirror," i.e., at the same point at which the reflection of the visual line took place. But if the mirror should move, and likewise the object seen by means of the mirror, while the beholder remains at rest, and if the two things in motion always remain at the same distance from the beholder, but with respect to one another are neither moving with equal speeds nor always at the same distance, then under these conditions it is impossible for the same appearance to occur in the same part of the mirror. For in practice it makes no difference whether the mirror and the thing seen are moving with unequal speeds, or one is in motion and the other at rest; and if this latter were the case, it is plain that the figure of the thing seen would appear now in one spot and now in another spot of the mirror, on account of the varying opposition according to position. And I say this, if the beholder is at rest: for if the beholder were to move, and the mirror remain at rest, while the object moved, then the figure of the thing seen could appear in the same spot on the mirror — since the beholder's motion could compensate for what was lacking due to the motion of the object seen, if they were thus proportionately moved. Hence, when the beholder remains at rest but the mirror and the thing seen are moved at unequal speeds, it is necessary that the figure not appear at the same spot on the mirror.
Sed astra quae sunt in circulo lacteo existentia, quae ponuntur quasi speculum, moventur; et similiter sol movetur, ad quem ponitur fieri repercussio visus, et sic obtinet locum rei visae; nos autem, qui sumus videntes, quiescimus, propter quietem terrae (motus autem quo movemur per terram, non facit aliquam sensibilem differentiam respectu tantae magnitudinis); astra autem praedicta et sol moventur aequaliter nobis quidem, et distantia eorum semper (est) aequalis nobis. Quod non est sic intelligendum, quod aequalis sit distantia a nobis ad solem, distantiae quae est a nobis ad stellas, cum supra dictum sit quod stellae sunt supra solem; sed quod sol per motum suum non fit a nobis magis vel minus distans. Et similiter convenit stellae: ut intelligatur maior vel minor distantia, quae sit notabilis respectu distantiae quae est inter solem et stellas; et hoc propter parvitatem terrae. Sed a seipsis sol et stellae non semper distant aequaliter: quia Delphis, hoc est constellatio delphini, quae est in lacteo circulo, quandoque oritur in media nocte, quandoque autem diluculo; et manifestum est quod plus distat a sole quando oritur in media nocte, quam quando oritur diluculo. Sed partes lactei circuli semper manent in eodem loco: quod non oportebat si esset apparitio ex repercussione proveniens; non enim esset haec claritas in eisdem locis, ut ostensum est. Unde patet praedictam opinionem esse falsam. But the stars in the milky circle that are assumed to be a mirror, are in motion; moreover, there is motion of the sun, to which a reflection of our vision is assumed to take place'(the sun therefore plays the role of the thing seen); but we, the beholders, are at rest, because the earth is at rest (for the motion involved by our moving about on the earth makes no perceptible difference with respect to so great a size. Furthermore, the stars in question and the sun are equally moved in relation to us and their distance from us always remains the same. This does not mean that our distance from the sun is equal to our distance from the stars (for it has been previously said that the stars are higher than the sun), but that the sun, by its motion, does not increase or decrease its distance from us. And the same is true of a star. And by a "greater or less distance" is to be understood a distance that is significant with respect to the distance between the sun and the stars: we say this because of the smallness of the earth. But in relation to one another, the sun and the stars are not always equidistant: because "Delphis," i.e., the constellation of the Dolphin, which is in the milky circle, rises sometimes in the middle of the night and sometimes at dawn; and it is plain that this constellation is farther from the sun when it appears at night than when it appears at dawn. But the parts of the milky circle remain forever in the same place — which should not be the case if it were an appearance caused by a reflexion; for this brightness would not exist in the same place, as has been shown. Hence it is plain that the aforesaid theory is false.
Secundam rationem ponit ibi: adhuc autem nocte et cetera. Et dicit quod de nocte in aqua et aliis huiusmodi corporibus specularibus aspicitur forma lactei circuli. Sed inconveniens est dicere quod tunc visus repercutiatur ab aqua ad solem: vel propter distantiam enim videtur valde inconveniens quod sint ibi duae repercussiones, una scilicet ab aqua ad lacteum circulum, et alia a lacteo circulo ad solem. 85. He gives the second reason [83] and says that at night the form of the milky circle appears in water and other such mirror-like bodies. But it is inadmissible to say that in these cases vision is reflected by the water to the sun — in other words, considering the distances involved, it seems most unacceptable that there should be two reflections: one, namely, from the water to the milky circle, and another from the milky circle to the sun.
Ultimo autem epilogando concludit quod lacteus circulus neque est via alicuius planetarum, ut prima opinio dixit; neque est lumen stellarum quae non respiciuntur a sole, ut dixit secunda opinio; neque est repercussio visus a stellis ad solem, ut dixit tertia opinio. Hae enim opiniones fuerunt ante eum de Galaxia. Finally, in summary he concludes that the milky circle is neither the path of any of the planets, as the first opinion held; nor the light of certain stars not regarded by the sun, as the second opinion said; nor the reverberation of our vision from the stars to the sun, as the third opinion maintained. And before his time these were the prevailing opinions about the "galaxy" [Milky Way].

Lecture 13
The Milky Way, according to Aristotle
Chapter 8 cont.
ἡμεῖς δὲ λέγωμεν ἀναλαβόντες τὴν ὑποκειμένην ἀρχὴν ἡμῖν. εἴρηται γὰρ πρότερον ὅτι τὸ ἔσχατον τοῦ λεγομένου ἀέρος δύναμιν ἔχει πυρός, ὥστε τῇ κινήσει διακρινομένου τοῦ ἀέρος ἀποκρίνεσθαι τοιαύτην σύστασιν οἵαν καὶ τοὺς κομήτας ἀστέρας εἶναί φαμεν. 85 Let us recall our fundamental principle and then explain our views. We have already laid down that the outermost part of what is called the air is potentially fire and that therefore when the air is dissolved by motion, there is separated off a kind of matter—and of this matter we assert that comets consist.
τοιοῦτον δὴ δεῖ νοῆσαι γιγνόμενον ὅπερ ἐπ' ἐκείνων, ὅταν μὴ αὐτὴ (346a.) καθ' αὑτὴν γένηται ἡ τοιαύτη ἔκκρισις, ἀλλ' ὑπό τινος τῶν ἄστρων ἢ τῶν ἐνδεδεμένων ἢ τῶν πλανωμένων τότε γὰρ οὗτοι φαίνονται κομῆται διὰ τὸ παρακολουθεῖν αὐτῶν τῇ φορᾷ ὥσπερ τῷ ἡλίῳ τὴν τοιαύτην σύγκρισιν, ἀφ' ἧς διὰ τὴν ἀνάκλασιν τὴν ἅλω φαίνεσθαί φαμεν, ὅταν οὕτω τύχῃ κεκραμένος ὁ ἀήρ. 86 We must suppose that what happens is the same as in the case of the comets when the matter does not form independently but is formed by one of the fixed stars or the planets. Then these stars appear to be fringed, because matter of this kind follows their course. In the same way, a certain kind of matter follows the sun, and we explain the halo as a reflection from it when the air is of the right constitution.
ὃ δὴ καθ' ἕνα συμβαίνει τῶν ἀστέρων, τοῦτο δεῖ λαβεῖν γιγνόμενον περὶ ὅλον τὸν οὐρανὸν καὶ τὴν ἄνω φορὰν ἅπασαν εὔλογον γάρ, εἴπερ ἡ ἑνὸς ἄστρου κίνησις, καὶ τὴν τῶν πάντων ποιεῖν τι τοιοῦτον καὶ ἐκριπίζειν ἀέρα τε καὶ διακρίνειν διὰ τὸ τοῦ κύκλου μέγεθος. <ἀνάγκη τοίνυν τῶν αὐτῶν μεγίστων κύκλων μάλιστα τὴν μέλλουσαν τοῦτο ποιήσειν φοράν. . . χρὴ γὰρ τοῦτο, ἵνα πολλὴ κίνησις ᾖ διὰ τὸ μέγεθος γιγνομένη καὶ πλείονα τὴν ἔξαψιν ποιήσῃ.> καὶ πρὸς τούτοις ἔτι καθ' ὃν τόπον πυκνότατα καὶ πλεῖστα καὶ μέγιστα τυγχάνουσιν ὄντα τῶν ἄστρων. 87 Now we must assume that what happens in the case of the stars severally happens in the case of the whole of the heavens and all the upper motion. For it is natural to suppose that, if the motion of a single star excites a flame, that of all the stars should have a similar result, and especially in that region in which the stars are biggest and most numerous and nearest to one another.
ὁ μὲν οὖν τῶν ζῳδίων διὰ τὴν τοῦ ἡλίου φορὰν καὶ τὴν τῶν πλανητῶν διαλύει τὴν τοιαύτην σύστασιν διόπερ οἱ πολλοὶ τῶν κομητῶν ἐκτὸς γίγνονται τῶν τροπικῶν. ἔτι δ' οὔτε περὶ τὸν ἥλιον οὔτε περὶ σελήνην γίγνεται κόμη θᾶττον γὰρ διακρίνουσιν ἢ ὥστε συστῆναι τοιαύτην σύγκρισιν. οὗτος δ' ὁ κύκλος ἐν ᾧ τὸ γάλα φαίνεται τοῖς ὁρῶσιν, ὅ τε μέγιστος ὢν τυγχάνει καὶ τῇ θέσει κείμενος οὕτως ὥστε πολὺ τοὺς τροπικοὺς ὑπερβάλλειν. πρὸς δὲ τούτοις ἄστρων ὁ τόπος πλήρης ἐστὶν τῶν μεγίστων καὶ λαμπροτάτων, καὶ ἔτι τῶν σποράδων καλουμένων (τοῦτο δ' ἐστὶν καὶ τοῖς ὄμμασιν ἰδεῖν φανερόν), ὥστε διὰ ταῦτα συνεχῶς καὶ ἀεὶ ταύτην πᾶσαν ἀθροίζεσθαι τὴν σύγκρισιν. 88 Now the circle of the zodiac dissolves this kind of matter because of the motion of the sun and the planets, and for this reason most comets are found outside the tropic circles. Again, no fringe appears round the sun or moon: for they dissolve such matter too quickly to admit of its formation. But this circle in which the milky way appears to our sight is the greatest circle, and its position is such that it extends far outside the tropic circles. Besides the region is full of the biggest and brightest constellations and also of what called 'scattered' stars (you have only to look to see this clearly). So for these reasons all this matter is continually and ceaselessly collecting there.
σημεῖον δέ καὶ γὰρ αὐτοῦ τοῦ κύκλου πλέον τὸ φῶς ἐστιν ἐν θατέρῳ ἡμικυκλίῳ τῷ τὸ δίπλωμα ἔχοντι ἐν τούτῳ γὰρ πλείω καὶ πυκνότερά ἐστιν ἄστρα ἢ ἐν θατέρῳ, ὡς οὐ δι' ἑτέραν τιν' αἰτίαν γιγνομένου τοῦ φέγγους ἢ διὰ τὴν τῶν ἄστρων φοράν εἰ γὰρ ἔν τε τῷ κύκλῳ τούτῳ γίγνεται ἐν ᾧ τὰ πλεῖστα κεῖται τῶν ἄστρων, καὶ αὐτοῦ τοῦ κύκλου ἐν ᾧ μᾶλλον φαίνεται καταπεπυκνῶσθαι καὶ μεγέθει καὶ πλήθει ἀστέρων, ταύτην εἰκὸς ὑπολαβεῖν οἰκειοτάτην αἰτίαν εἶναι τοῦ πάθους. θεωρείσθω δ' ὅ τε κύκλος καὶ τὰ ἐν αὐτῷ ἄστρα ἐκ τῆς ὑπογραφῆς. τοὺς δὲ σποράδας καλουμένους οὕτω μὲν εἰς τὴν σφαῖραν οὐκ ἔσται τάξαι διὰ τὸ μηδεμίαν διὰ τέλους ἔχειν φανερὰν ἕκαστον θέσιν, εἰς δὲ τὸν οὐρανὸν ἀναβλέπουσίν ἐστι δῆλον ἐν μόνῳ γὰρ τούτῳ τῶν κύκλων τὰ μεταξὺ πλήρη τοιούτων ἀστέρων ἐστίν, ἐν δὲ τοῖς ἄλλοις διαλείπει (346b.) φανερῶς. 89 A proof of the theory is this: In the circle itself the light is stronger in that half where the milky way is divided, and in it the constellations are more numerous and closer to one another than in the other half; which shows that the cause of the light is the motion of the constellations and nothing else. For if it is found in the circle in which there are most constellations and at that point in the circle at which they are densest and contain the biggest and the most stars, it is natural to suppose that they are the true cause of the affection in question. The circle and the constellations in it may be seen in the diagram. The so-called 'scattered' stars it is not possible to set down in the same way on the sphere because none of them have an evident permanent position; but if you look up to the sky the point is clear. For in this circle alone are the intervals full of these stars: in the other circles there are obvious gaps.
ὥστ' εἴπερ καὶ περὶ τοῦ φαίνεσθαι κομήτας ἀποδεχόμεθα τὴν αἰτίαν ὡς εἰρημένην μετρίως, καὶ περὶ τοῦ γάλακτος τὸν αὐτὸν ὑποληπτέον τρόπον ἔχειν ὃ γὰρ ἐκεῖ περὶ ἕνα ἐστὶν πάθος ἡ κόμη, τοῦτο περὶ κύκλον τινὰ συμβαίνει γίγνεσθαι τὸ αὐτό, καὶ ἔστιν τὸ γάλα, ὡς εἰπεῖν οἷον ὁριζόμενον, ἡ τοῦ μεγίστου διὰ τὴν ἔκκρισιν κύκλου κόμη. διὸ καθάπερ πρότερον εἴπομεν, οὐ πολλοὶ οὐδὲ πολλάκις γίγνονται κομῆται, διὰ τὸ συνεχῶς ἀποκεκρίσθαι καὶ ἀποκρίνεσθαι καθ' ἑκάστην περίοδον εἰς τοῦτον τὸν τόπον αἰεὶ τὴν τοιαύτην σύστασιν. 90 Hence if we accept the cause assigned for the appearance of comets as plausible we must assume that the same kind of thing holds good of the milky way. For the fringe which in the former case is an affection of a single star here forms in the same way in relation to a whole circle. So if we are to define the milky way we may call it 'a fringe attaching to the greatest circle, and due to the matter secreted'. This, as we said before, explains why there are few comets and why they appear rarely; it is because at each revolution of the heavens this matter has always been and is always being separated off and gathered into this region.
περὶ μὲν οὖν τῶν γιγνομένων ἐν τῷ περὶ τὴν γῆν κόσμῳ τῷ συνεχεῖ ταῖς φοραῖς εἴρηται, περί τε τῆς διαδρομῆς τῶν ἄστρων καὶ τῆς ἐκπιμπραμένης φλογός, ἔτι δὲ περί τε κομητῶν καὶ τοῦ καλουμένου γάλακτος σχεδὸν γάρ εἰσιν τοσαῦτα τὰ πάθη τὰ φαινόμενα περὶ τὸν τόπον τοῦτον. 91 We have now explained the phenomena that occur in that part of the terrestrial world which is continuous with the motions of the heavens, namely, shooting-stars and the burning flame, comets and the milky way, these being the chief affections that appear in that region.
Reprobatis opinionibus aliorum de circulo lacteo, hic ponit propriam opinionem. Et circa hoc duo facit: 86. Having rejected the opinion of others about the milky circle, he now presents his own opinion. About this he does two things:

primo resumit quaedam superius dicta, quae sunt utilia ad propositum manifestandum;

secundo manifestat propositum, ibi: quod itaque secundum unum astrorum accidit et cetera.

First, he recalls previous statements useful for explaining the proposition;

Secondly, he manifests the proposition, at 88.

Resumit autem duo: primo quidem quod supra dictum est de positione siccae exhalationis, et eius inflammatione. Unde dicit quod vult resumere id quod supra posuit tanquam principium. Dictum est enim supra quod communiter vocatur aer totum hoc quod est intra terram et globum lunarem; huius autem suprema pars, licet non proprie possit dici ignis, quia ignis significat excessum in caliditate, sicut glacies in frigore, tamen illa pars superior aeris habet virtutem ignis, quia est calida et sicca; ita quod, cum aer per motum caelestem disgregatur, talis consistentia exhalationis praedictae segregatur a terra et ab aere inferiori, et elevatur sursum, et ex hoc dicimus apparere stellas cometas. He recalls two things: first, what was previously said about the location of the dry exhalation and of its kindling [85]. Hence he says that he wants to recall what he previously laid down as a principle. For it has been previously said that everything between earth and the globe of the moon has the common name of "air," while the highest part thereof, although it cannot strictly be called "fire" (because fire denotes a superabundance of heat, just as does ice with respect to cold), yet that upper part of the air does have the virtue of fire, because it is hot and dry — with the result that, when the air is separated by the heavenly motion, a certain consistency of the exhalation already mentioned is collected from the earth and lower air and lifted upward; and we say that it is from this that comet stars appear.
Secundo ibi: tale itaque oportet etc., resumit quod dictum est supra de uno modo apparitionis cometae. Et dicit quod oportet intelligere aliquid simile esse in lacteo circulo, quod fit in cometis, quando cometa non fuerit aliqua exhalatio elevata et ignita per se existens absque aliqua stella, sed fit eius apparitio ab aliqua stellarum fixarum vel errantium, sicut dictum est. Quia tunc apparent cometae propter hoc, quod tales exhalationes elevatae consequuntur motum stellarum quae videntur cometae; sicut etiam solem sequitur talis adunata exhalatio, ex qua, propter repercussionem radiorum, apparet halo, cum aer ad hoc fuerit dispositus. 87. Secondly [86], he recalls what he previously said concerning one of the ways that account for the appearance of a comet. And he says that we should understand in the milky circle something akin to what takes place in comets when the comet is not an exhalation borne aloft and ignited, and existing by itself apart from any star, but is an apparition deriving from one of the fixed or wandering stars, as was said. For in those cases comets appear because such elevated exhalations accompany the course of the stars that appear as comets; just as the sun is accompanied by such a collected exhalation, from which, as a result of reflected rays, a halo appears, when the air is disposed for such.
Deinde cum dicit: quod itaque secundum unum astrorum accidit etc., manifestat propositum, ostendens quae sit causa apparitionis lactei circuli. Et circa hoc tria facit: 88. Then [87] he manifests the proposition, showing what is the cause of the appearance of the milky circle. About this he does three things;

primo proponit causam apparitionis lactei circuli;

secundo inducit signum eorum quae dicta sunt, ibi: signum autem etc.;

tertio concludit propositum, ibi: quare si quidem et cetera.

First, he proposes the cause of the appearance of the milky circle;

Secondly, he introduces a sign to support what he said, at 90;

Thirdly, he concludes the proposition, at 92.

Circa primum duo facit. Primo ostendit causam apparitionis lactei circuli. Et dicit quod illud quod accidit in apparitione secundum unam stellam, oportet accipere esse factum circa totum caelum et circa totum motum ipsius: quia rationabile est quod, si motus unius stellae attrahit et circumducit aliquam exhalationem, quod multo magis hoc possit facere motus omnium stellarum; et praecipue in loco illo caeli, ubi apparent frequentissimae stellae et plurimae et maximae. Regarding the first he does two things. First, he shows the cause of the appearance of the milky circle [87] and says that what happens with respect to the appearance of one star should be understood as happening with respect to the entire heaven and its entire course — because it is reasonable, if the motion of one star attracts and carries an exhalation along, that this should be all the more true of the motion of all the stars, and especially in that region of the heaven where there appears a very large collection of stars, greatest both in number and size.
Secundo ibi: qui quidem igitur animalium etc., ostendit causam quare in hac determinata parte caeli circuli lactei claritas apparet. Et dicit quod circulus animalium, qui dicitur zodiacus, dissolvit adunationem praedictae exhalationis, propter hoc quod per zodiacum movetur sol et alii planetae. Et haec est etiam causa propter quam, ut plurimum, cometae non apparent in zodiaco, sed extra tropicos, ut dictum est. 89. Secondly [88], he shows the cause why it is in that determinate part of the heaven that the brightness of the milky circle appears. And he says that the circle of the animals, called the "Zodiac," dissolves the accumulated mass of the above-mentioned exhalation, because of the fact that the sun and the other planets are moved through the Zodiac. This also explains why, for the most part, comets do not appear in the Zodiac, but outside the tropics, as was said.
Et haec est etiam causa propter quam circa solem et lunam non fit coma: quia videlicet per motum solis et lunae citius disgregatur exhalatio (quam diximus esse causam apparitionis cometae et lactei circuli), quam ut possit adunari ad causandum apparitiones praedictas. Sed iste circulus in quo apparet nobis videntibus lactea claritas, et est unus maximorum circulorum, quia dividit sphaeram per medium; et est sic dispositus secundum situm, ut ex utraque parte multum excedat utrumque tropicum, scilicet hiemalem et aestivum, licet intersecetur a zodiaco. Et etiam hic locus istius circuli est plenus magnis stellis fulgidis, et quae propter frequentiam et spissitudinem vocantur sporadicae, idest seminatae in caelo (quod etiam manifeste oculis videri potest); ita quod propter huiusmodi causam semper in tali parte caeli adunetur exhalatio; quia videlicet in hac parte caeli est efficax virtus stellarum ad attrahendam exhalationem, et non est causa vehemens quae impediat eius adunationem, sicut accidit sub zodiaco circulo. Ista igitur exhalatio adunata sub tali parte caeli, facit ibi videri lacteam claritatem, sicut et exhalatio consequens aliquam stellam, facit ibi videri comam. Moreover, this also is the cause why no fringe [coma] appears around the sun and moon: namely, because the motions of the sun and moon separate the exhalation (which we have said to cause the appearance of a comet and of the milky circle) faster than it can accumulate to cause these appearances. But that circle in which a milky brightness appears to us observers is both one of the greatest circles (for it divides the sphere in half), and is so located that in both directions it far exceeds both the tropic circles, namely, the winter and the summer one, even though it is intersected by the Zodiac. Moreover, this place of that circle is filled with bright stars so numerous and thick that they are called "sporadic," i.e., sowed in the heaven (this can be observed with the naked eye); as a result, an exhalation is always gathered together in such an area of the heaven, since, namely, there is in this region of the heaven stellar virtue powerful enough to attract the exhalation, and no vehement cause impeding its accumulating, as happens in the zodiacal circle. Accordingly, the exhalation accumulated in that region of the heaven causes a milky brightness to be seen there, just as the exhalation accompanying a star makes a fringe appear.
Deinde cum dicit: signum autem etc., manifestat quod dictum est, per signum: dicens quod signum praedictorum est, quod in ipso lacteo circulo unus eius semicirculus duplatur, et habet amplius de lumine. Cuius causa est, quia in illo semicirculo sunt plures stellae et magis frequentes quam in alio, ac si nulla esset alia causa claritatis apparentis, quam motus astrorum plurimorum frequentium. Quia si in isto circulo apparet claritas in quo plures stellae ponuntur, et in illa eius parte plus apparet in qua sunt stellae plures et magis frequentes, verisimile est multitudinem stellarum esse causam huius apparitionis. 90. Then [89] he shows what he has said with a sign, and says that a sign of the foregoing is that in the milky circle one of its semicircles is doubled and has more light. The reason for this is that in that semicircle there are more stars there and closer together than in the other semicircle, as though there were no other cause of the visible brightness than the movements of a great many clustered stars. For if a brightness appears in that circle in which there are more stars, and if more brightness appears in that section in which the stars are more numerous and closer together, it is reasonable that it is the multitude of stars that causes this appearance.
Quod autem dictum est de isto circulo et de stellis in eo existentibus, potest considerari ex descriptione: quia astrologi describunt totam sphaeram cum stellis in ea existentibus. What was said of the circle itself, and of the stars existing in it, can be seen from the diagram — since the astronomers have drawn charts of the whole sphere and of the constellations in it.
Exponit autem consequenter quare stellae in circulo lacteo existentes vocantur sporadicae, idest seminatae: quia videlicet sic sunt dispersae per illam partem caeli, quod non contingit eas ordinare sub aliqua figuratione, sicut stellas existentes in aliis partibus caeli; quia unaquaeque earum non habet aliquam determinatam positionem, ut possit ad similitudinem alicuius figurae reduci. Et hoc manifestum est aspicienti in caelo: quia in solo hoc circulo spatia intermedia inter stellas maiores, sunt plena quibusdam parvis stellis; sed in aliis locis caeli manifeste deficiunt stellae, quapropter intermedia apparent vacua a stellis. 91. Then he explains why the stars in the milky circle are called "sporadic," i.e., scattered like seeds: it is because they are scattered through that region of the heaven in such a way that they do not allow being grouped under some figure as do the stars existing in other regions of the heaven, since each of them does not have a fixed position so that they could be reduced into the likeness of some figure. This is plain to anyone looking at the heaven: because it is only in this circle that the areas between the major stars are filled with certain small stars; while in other regions of the heaven stars are manifestly lacking, so that the intervening spaces appear empty of stars.
Deinde cum dicit: quare si quidem etc., concludit ex supradictis suam intentionem. Et dicit quod si causa supra assignata de apparitione cometae, acceptanda est tanquam mediocriter dicta (quia scilicet nullum habet inconveniens manifestum), existimandum est etiam sic se habere de circulo lacteo: quia quod in cometis est coma circa unam stellam, eandem passionem accidit fieri circa quendam circulum. Ita quod lactea claritas, ut ita dicatur quasi definiendo, nihil aliud sit (lactea via) quam coma eiusdem maximi circuli, in caelo apparens propter segregationem, idest elevationem a terra, exhalationis ad illam partem adunatae. Et ideo, sicut prius dictum est, non fiunt multi cometae neque frequenter, quia talis adunatio exhalationis quae elevata est a terra, elevatur secundum unamquamque circulationem, et adunatur maxime in loco lactei circuli; ita quod a lacteo circulo exhalatio superabundans non relinquitur, quae possit esse materia apta ad cometae apparitionem. 92. Then [90] he concludes his intention from the foregoing. And he says that if the cause assigned above of the comet's appearance is accepted as plausible (because it involves no manifest inconsistencies), the same should be accorded this explanation of the milky circle: because what, in the case of comets, is a fringe about one star, is here a corresponding passion affecting some one circle. Thus, the milky clarity, if one were, so to speak, to define it, would be, as the milky way, nothing other than a fringe [coma] of the same greatest circle, appearing in the heaven on account of the "separating," i.e., the lifting from the earth, of an exhalation concentrated in that area. And therefore, as was already stated, many comets are not produced and they do not appear frequently, since such a gathering of the exhalation elevated from the earth is drawn up in accord with each revolution and brought together mostly in the region of the milky circle, in such a way that no surplus exhalation is left over from the milky circle which could be material suitable for the appearance of a comet.
Ultimo autem recapitulat ea quae dicta sunt. Et dicit quod dictum est de his quae fiunt in hoc mundo qui est circa terram, qui scilicet est suppositus generationi et corruptioni, quantum ad illum locum qui est continuus, idest contiguus, motibus caelestibus: scilicet de discursu astrorum, et de ignita flamma, et de cometis et lacteo circulo; quia huiusmodi passiones apparent circa locum istum superiorem. 93. Finally he sums up what has been said [91] and says that we have spoken of the things that take place in the earth-environing world, which is subject, namely, to generation and corruption, as to that region which is "continuous," i.e., contiguous, to the heavenly movements: of the shooting of stars and of the burning flame and of comets and the milky circle, because such passions appear in that upper region.

Lecture 14
The causes in general of phenomena generated by the moist exhalation in the lower part of the air. Of rain, dew and frost
Chapter 9
περὶ δὲ τοῦ τῇ θέσει μὲν δευτέρου τόπου μετὰ τοῦτον, πρώτου δὲ περὶ τὴν γῆν, λέγωμεν οὗτος γὰρ κοινὸς ὕδατός τε τόπος καὶ ἀέρος καὶ τῶν συμβαινόντων περὶ τὴν ἄνω γένεσιν αὐτοῦ. ληπτέον δὲ καὶ τούτων τὰς ἀρχὰς καὶ τὰς αἰτίας πάντων ὁμοίως. 92 Let us go on to treat of the region which follows next in order after this and which immediately surrounds the earth. It is the region common to water and air, and the processes attending the formation of water above take place in it. We must consider the principles and causes of all these phenomena too as before.
ἡ μὲν οὖν ὡς κινοῦσα καὶ κυρία καὶ πρώτη τῶν ἀρχῶν ὁ κύκλος ἐστίν, ἐν ᾧ φανερῶς ἡ τοῦ ἡλίου φορὰ διακρίνουσα καὶ συγκρίνουσα τῷ γίγνεσθαι πλησίον ἢ πορρώτερον αἰτία τῆς γενέσεως καὶ τῆς φθορᾶς ἐστι. 93 The efficient and chief and first cause is the circle in which the sun moves. For the sun as it approaches or recedes, obviously causes dissipation and condensation and so gives rise to generation and destruction.
μενούσης δὲ τῆς γῆς, τὸ περὶ αὐτὴν ὑγρὸν ὑπὸ τῶν ἀκτίνων καὶ ὑπὸ τῆς ἄλλης τῆς ἄνωθεν θερμότητος ἀτμιδούμενον φέρεται ἄνω 94 Now the earth remains but the moisture surrounding it is made to evaporate by the sun's rays and the other heat from above, and rises.
τῆς δὲ θερμότητος ἀπολιπούσης τῆς ἀναγούσης αὐτό, καὶ τῆς μὲν διασκεδαννυμένης πρὸς τὸν ἄνω τόπον, τῆς δὲ καὶ σβεννυμένης διὰ τὸ μετεωρίζεσθαι πορρώτερον εἰς τὸν ὑπὲρ τῆς γῆς ἀέρα, συνίσταται πάλιν ἡ ἀτμὶς ψυχομένη διά τε τὴν ἀπόλειψιν τοῦ θερμοῦ καὶ τὸν τόπον, καὶ γίγνεται ὕδωρ ἐξ ἀέρος γενόμενον δὲ πάλιν φέρεται πρὸς τὴν γῆν. 95 But when the heat which was raising it leaves it, in part dispersing to the higher region, in part quenched through rising so far into the upper air, then the vapour cools because its heat is gone and because the place is cold, and condenses again and turns from air into water. And after the water has formed it falls down again to the earth.
ἔστι δ' ἡ μὲν ἐξ ὕδατος ἀναθυμίασις ἀτμίς, ἡ δ' ἐξ ἀέρος εἰς ὕδωρ νέφος ὁμίχλη δὲ νεφέλης περίττωμα τῆς εἰς ὕδωρ συγκρίσεως. διὸ σημεῖον μᾶλλόν ἐστιν εὐδίας ἢ ὑδάτων οἷον γάρ ἐστιν ἡ ὁμίχλη νεφέλη ἄγονος. 96 The exhalation of water is vapour: air condensing into water is cloud. Mist is what is left over when a cloud condenses into water, and is therefore rather a sign of fine weather than of rain; for mist might be called a barren cloud.
γίγνεται δὲ κύκλος οὗτος μιμούμενος τὸν τοῦ ἡλίου κύκλον ἅμα γὰρ (347a.) ἐκεῖνος εἰς τὰ πλάγια μεταβάλλει καὶ οὗτος ἄνω καὶ κάτω. δεῖ δὲ νοῆσαι τοῦτον ὥσπερ ποταμὸν ῥέοντα κύκλῳ ἄνω καὶ κάτω, κοινὸν ἀέρος καὶ ὕδατος πλησίον μὲν γὰρ ὄντος τοῦ ἡλίου ὁ τῆς ἀτμίδος ἄνω ῥεῖ ποταμός, ἀφισταμένου δὲ ὁ τοῦ ὕδατος κάτω. καὶ τοῦτ' ἐνδελεχὲς ἐθέλει γίγνεσθαι κατά γε τὴν τάξιν ὥστ' εἴπερ ᾐνίττοντο τὸν ὠκεανὸν οἱ πρότερον, τάχ' ἂν τοῦτον τὸν ποταμὸν λέγοιεν τὸν κύκλῳ ῥέοντα περὶ τὴν γῆν. 97 So we get a circular process that follows the course of the sun. For according as the sun moves to this side or that, the moisture in this process rises or falls. We must think of it as a river flowing up and down in a circle and made up partly of air, partly of water. When the sun is near, the stream of vapour flows upwards; when it recedes, the stream of water flows down: and the order of sequence, at all events, in this process always remains the same. So if 'Oceanus' had some secret meaning in early writers, perhaps they may have meant this river that flows in a circle about the earth.
ἀναγομένου δὲ τοῦ ὑγροῦ αἰεὶ διὰ τὴν τοῦ θερμοῦ δύναμιν καὶ πάλιν φερομένου κάτω διὰ τὴν ψύξιν πρὸς τὴν γῆν, οἰκείως τὰ ὀνόματα τοῖς πάθεσιν κεῖται καί τισιν διαφοραῖς αὐτῶν ὅταν μὲν γὰρ κατὰ μικρὰ φέρηται, ψακάδες, ὅταν δὲ κατὰ μείζω μόρια, ὑετὸς καλεῖται. 98 So the moisture is always raised by the heat and descends to the earth again when it gets cold. These processes and, in some cases, their varieties are distinguished by special names. When the water falls in small drops it is called a drizzle; when the drops are larger it is rain.
Chapter 10
ἐκ δὲ τοῦ καθ' ἡμέραν ἀτμίζοντος ὅσον ἂν μὴ μετεωρισθῇ δι' ὀλιγότητα τοῦ ἀνάγοντος αὐτὸ πυρὸς πρὸς τὸ ἀναγόμενον ὕδωρ, πάλιν καταφερόμενον ὅταν ψυχθῇ νύκτωρ, καλεῖται δρόσος καὶ πάχνη, 99 Some of the vapour that is formed by day does not rise high because the ratio of the fire that is raising it to the water that is being raised is small. When this cools and descends at night it is called dew and hoar-frost.
πάχνη μὲν ὅταν ἡ ἀτμὶς παγῇ πρὶν εἰς ὕδωρ συγκριθῆναι πάλιν (γίγνεται δὲ χειμῶνος, καὶ μᾶλλον ἐν τοῖς χειμερινοῖς τόποις), δρόσος δ' ὅταν συγκριθῇ εἰς ὕδωρ ἡ ἀτμίς, καὶ μήθ' οὕτως ἔχῃ ἡ ἀλέα ὥστε ξηρᾶναι τὸ ἀναχθέν, μήθ' οὕτω ψῦχος ὥστε παγῆναι τὴν ἀτμίδα αὐτὴν διὰ τὸ ἢ τὸν τόπον ἀλεεινότερον ἢ τὴν ὥραν εἶναι γίγνεται γὰρ μᾶλλον ἡ δρόσος ἐν εὐδίᾳ καὶ ἐν τοῖς εὐδιεινοτέροις τόποις, ἡ δὲ πάχνη, καθάπερ εἴρηται, τοὐναντίον δῆλον γὰρ ὡς ἡ ἀτμὶς θερμότερον ὕδατος (ἔχει γὰρ τὸ ἀνάγον ἔτι πῦρ), ὥστε πλείονος ψυχρότητος αὐτὴν πῆξαι. 100 When the vapour is frozen before it has condensed to water again it is hoar-frost; and this appears in winter and is commoner in cold places. It is dew when the vapour has condensed into water and the heat is not so great as to dry up the moisture that has been raised nor the cold sufficient (owing to the warmth of the climate or season) for the vapour itself to freeze. For dew is more commonly found when the season or the place is warm, whereas the opposite, as has been said, is the case with hoar-frost. For obviously vapour is warmer than water, having still the fire that raised it: consequently more cold is needed to freeze it.
γίγνεται δ' ἄμφω αἰθρίας τε καὶ νηνεμίας οὔτε γὰρ ἀναχθήσεται μὴ οὔσης αἰθρίας, οὔτε συστῆναι δύναιτ' ἂν ἀνέμου πνέοντος. σημεῖον δ' ὅτι γίγνεται ταῦτα διὰ τὸ μὴ πόρρω μετεωρίζεσθαι τὴν ἀτμίδα ἐν γὰρ τοῖς ὄρεσιν οὐ γίγνεται πάχνη. 101 Both dew and hoar-frost are found when the sky is clear and there is no wind. For the vapour could not be raised unless the sky were clear, and if a wind were blowing it could not condense.
αἰτία δὲ μία μὲν αὕτη, ὅτι ἀνάγεται ἐκ τῶν κοίλων καὶ ἐφύδρων τόπων, ὥστε καθάπερ φορτίον φέρουσα πλέον ἡ ἀνάγουσα θερμότης ἢ καθ' ἑαυτὴν οὐ δύναται μετεωρίζειν ἐπὶ πολὺν τόπον αὐτὸ τοῦ ὕψους, ἀλλ' ἐγγὺς ἀφίησι πάλιν ἑτέρα δ' ὅτι καὶ ῥεῖ μάλιστα ὁ ἀὴρ ῥέων ἐν τοῖς ὑψηλοῖς, ὃς διαλύει τὴν σύστασιν τὴν τοιαύτην. 102 The fact that hoar-frost is not found on mountains contributes to prove that these phenomena occur because the vapour does not rise high. One reason for this is that it rises from hollow and watery places, so that the heat that is raising it, bearing as it were too heavy a burden cannot lift it to a great height but soon lets it fall again. A second reason is that the motion of the air is more pronounced at a height, and this dissolves a gathering of this kind.
γίγνεται δ' ἡ δρόσος πανταχοῦ νοτίοις, οὐ βορείοις, πλὴν ἐν τῷ Πόντῳ. ἐκεῖ δὲ τοὐναντίον βορείοις μὲν γὰρ γίγνεται, νοτίοις δ' οὐ (347b.) γίγνεται. 103 Everywhere, except in Pontus, dew is found with south winds and not with north winds. There the opposite is the case and it is found with north winds and not with south.
αἴτιον δ' ὁμοίως ὥσπερ ὅτι εὐδίας μὲν γίγνεται, χειμῶνος δ' οὔ ὁ μὲν γὰρ νότος εὐδίαν ποιεῖ, ὁ δὲ βορέας χειμῶνα ψυχρὸς γάρ, ὥστ' ἐκ τοῦ χειμῶνος τῆς ἀναθυμιάσεως σβέννυσι τὴν θερμότητα. 104 The reason is the same as that which explains why dew is found in warm weather and not in cold. For the south wind brings warm, and the north, wintry weather. For the north wind is cold and so quenches the heat of the evaporation.
ἐν δὲ τῷ Πόντῳ ὁ μὲν νότος οὐχ οὕτως ποιεῖ εὐδίαν ὥστε γίγνεσθαι ἀτμίδα, ὁ δὲ βορέας διὰ τὴν ψυχρότητα ἀντιπεριιστὰς τὸ θερμὸν ἀθροίζει, ὥστε πλέον ἀτμίζει μᾶλλον. πολλάκις δὲ τοῦτο καὶ ἐν τοῖς ἔξω τόποις ἰδεῖν γιγνόμενον ἔστιν ἀτμίζει γὰρ τὰ φρέατα βορείοις μᾶλλον ἢ νοτίοις ἀλλὰ τὰ μὲν βόρεια σβέννυσιν πρὶν συστῆναί τι πλῆθος, ἐν δὲ τοῖς νοτίοις ἐᾶται ἀθροίζεσθαι ἡ ἀναθυμίασις. αὐτὸ δὲ τὸ ὕδωρ οὐ πήγνυται, καθάπερ ἐν τῷ περὶ τὰ νέφη τόπῳ. 105 But in Pontus the south wind does not bring warmth enough to cause evaporation, whereas the coldness of the north wind concentrates the heat by a sort of recoil, so that there is more evaporation and not less. This is a thing which we can often observe in other places too. Wells, for instance, give off more vapour in a north than in a south wind. Only the north winds quench the heat before any considerable quantity of vapour has gathered, while in a south wind the evaporation is allowed to accumulate. Water, once formed, does not freeze on the surface of the earth, in the way that it does in the region of the clouds.
Postquam philosophus determinavit de his quae causantur ex exhalatione sicca ad supremum locum aeris elevata, hic determinat de his quae causantur ex exhalatione humida. 94. After determining concerning phenomena caused from the hot exhalation lifted to the highest place of the air, the Philosopher here determines about phenomena caused from the moist exhalation.

Et primo de his quae causantur ex exhalatione humida super terram;

secundo de his quae causantur ex exhalatione humida in terra, ibi: de ventis autem et cetera.

First, about phenomena caused above the earth from the moist exhalation;

Secondly, about those caused on the earth from the moist exhalation (L. 16).

Circa primum duo facit. Primo ostendit de quo est intentio: dicens quod nunc dicendum est de his quae fiunt in loco qui secundum situm, descendendo, est secundus post locum supremum aeris, in quo fiunt ea quae dicta sunt, sed ascendendo est primus, immediatus circa terram; quae inferior pars aeris est. Iste enim locus est communis et aquae et aeri: quia in eo aer est secundum naturalem ordinem elementorum, et aqua ex vaporibus elevatis ibi generatur. Unde non solum est communis aquae et aeri, sed etiam eis quae accidunt circa generationem ipsius aquae et aeris, quae fiunt superius dum aqua resolvitur in vapores, qui pertinent ad naturam aeris, et vapores congregantur in aquam. Ostendit etiam modum determinandi de istis, dicens quod debemus sumere primo principia communia et causas omnium horum accidentium. 95. Regarding the first he does two things: first, he shows what his intention concerns [92] and says that we must now discuss the things which come to be in the region which, going downwards, is the second after the uppermost region of the air (where the phenomena already discussed take place), but which, going upward, is first, i.e., the region immediately around the earth: this region is the lower region of air. It is the region common both to water and to air; because in it air exists according to the natural order of the elements, and water is generated there from vapors borne aloft. Hence not only is it common to water and air, but also to the phenomena attending the generation of that water and air. These generations take place on high, when water is resolved into vapors (which pertain to the nature of air) and vapors are gathered into water. He also indicates the method for determining these matters and says that we should first take the common principles and causes of all these things that happen.
Secundo ibi: quod quidem igitur etc., determinat propositum. 96. Secondly [93] he determines the proposition.

Et primo ponit ea quae communiter pertinent ad causam omnium huiusmodi passionum;

secundo determinat de singulis passionibus, ostendens differentiam inter eas, ibi: elevato autem humido et cetera.

First, he posits what pertains commonly to the cause of all passions of this kind;

Secondly, he determines concerning each of them separately, showing wherein they differ, at 101.

Circa primum tria facit. Primo ponit causam effectivam harum passionum. Et dicit quod illud quod est causa sicut movens et principale et primum principium omnium harum passionum, est circulus zodiacus, in quo manifeste movetur sol, qui et disgregat resolvendo vapores a terra, et congregat eos per suam absentiam: frigore enim invalescente in aere per absentiam solis, nubes condensantur in aquam. Et ideo subiungit quod ex hoc quod quandoque fit prope nos, quandoque autem elongatur a nobis, existit causa generationis et corruptionis. Fit prope autem nobis secundum proprium motum, quando accedit ad signa Septentrionalia: elongatur autem a nobis, dum moratur in signis meridionalibus. About the first he does three things: first, he sets down the efficient cause of these passions [93] and says that all these passions have as their cause, in the sense of the movent, and primary, and first principle, the circle of the Zodiac in which the sun clearly moves, which both separates the vapors, by resolving them from earth, and unites them by its absence: for when coldness increases in the air on account of the sun's absence, clouds are condensed into water. Accordingly he adds that from its being at one time near us, and at another time away from us, the sun is the cause of generation and corruption. It gets near us, when by its own motion it approaches the northern signs; it is moved away from us, when it tarries in the southern signs.
Secundo ibi: manente autem terra etc., ostendit causam materialem harum passionum. Et dicit quod, cum terra quiescat in medio, illud humidum aqueum quod est circa ipsam, tum a radiis solis tum ab alia caliditate quae est a superioribus corporibus, resolvitur in vaporem, et sic subtiliatum per virtutem calidi sursum fertur. 97. Secondly [94], he shows the material cause of these passions and says that, since the earth is at rest in the center, the aqueous humor surrounding it is, both through the agency of the sun's rays and through other heat from the higher bodies, resolved into vapor and, being thus refined by the virtue of the heat, borne aloft.
Tertio ibi: caliditate autem etc., ostendit modum generationis horum de quibus intendit. Et circa hoc tria facit. Primo ponit in communi modum generationis harum passionum. Et dicit quod vapor qui sursum fertur per virtutem caloris, deseritur a caliditate quae sursum eum ferebat. Quod quidem contingit dupliciter: uno modo per hoc quod id quod erat subtilius et calidius in vapore, elevatur ulterius ad superiorem locum exhalationis siccae, et sic residua pars vaporis remanet frigida; alio modo per hoc quod calor qui est in vapore extinguitur, propter hoc quod longe elevatur a terra in aere qui est supra terram, ubi deficit calor propter hoc quod radii reverberati a terra in immensum sparguntur, ut supra dictum est. Sic igitur deficiente calore calefaciente et elevante vaporem aqueum, vapor aqueus redit ad suam naturam, coadunante etiam frigiditate loci; et sic infrigidatur, et infrigidatus inspissatur, et inspissatus cadit ad terram. 98. Thirdly [95], he shows the way in which the things under discussion are generated. About this he does three things: first, he states in general the way these passions are generated and says that the vapor borne aloft by the power of the heat is abandoned by the heat which bore it aloft. This happens in two ways: in one way by the fact that the finer and warmer elements in the vapor are raised higher still, to the upper region of the dry exhalation — consequently, the portion of vapor left behind remains cold; in another way by the fact that the heat in the vapor is quenched by having been lifted far from the earth, in the air above the earth where heat is feeble on account of the rays reflected from the earth being scattered far apart, as was stated above. Therefore, when the heat which warmed and elevated the moist vapor runs out, this vapor returns to its nature, with the coldness of the region condensing it; thus it becomes cool,-and after being cooled, it is thickened, and once thickened, it falls to earth.
Secundo ibi: est autem quae quidem etc., ostendit quid sit medium in praedictis transmutationibus. In prima enim transmutatione, secundum quam aqua subtiliatur et elevatur, medium est vapor: nam ipsa exhalatio resoluta ab aqua vocatur vapor, qui est medius inter aerem et aquam. In illa autem transmutatione secundum quam aer condensatur in aquam, medium est nubes, quae est via generationis aquae. Sed cum nubes condensatur in aquam, id quod est residuum de nube, quod scilicet in aquam condensari non potuit, est caligo nebulae. Et ideo nebula magis est signum serenitatis quam pluviae: quia nebula est quasi quaedam nubes sterilis, idest sine pluvia, quae est naturalis effectus nubis. Contingit tamen aliquando nebulam elevari in ipsa exhalatione vaporum, antequam condensentur in nubem perfecte: et tunc nebula potest esse signum pluviae. 99. Secondly [96] he shows what intermediates are involved in these transmutations. In the first transmutation, in which water is subtilized and raised up, the intermediate is vapor: for the very exhalation resolved from the water is called "vapor," which is intermediate between air and water. In that transmutation in which air is condensed into water, the medium is a cloud, which is a step toward the generation of water. But when the cloud is condensed into water, that which is left over in the cloud, i.e., whatever could not be condensed into water, is called the fog of mist. That is why mist is more a sign of clear than of rainy weather: for mist is, as it were, a "barren" cloud, i.e., devoid of rain, which is the natural effect of a cloud. However it sometimes happens that mist is carried up along with the vaporous exhalations before they are perfectly condensed into a cloud — and then mist can be a sign of rain.
Tertio ibi: fit autem circulus iste etc., ostendit quomodo in praedictis transmutationibus representatur similitudo primae causae moventis, scilicet circulationis solis. Attenditur enim quaedam circulatio in praedictis transmutationibus, dum aqua resolvitur in vapores, qui condensantur in nubes, et nubes in aquam, quae cadit in terram. Dicit ergo quod ista circularis transmutatio imitatur circularem motum solis: sol enim permutatur ad diversas partes caeli, puta ad Septentrionem et meridiem, et circulatio ista completur in hoc quod vapores ascendunt sursum et descendunt deorsum. Sed oportet intelligere quod iste fluxus vaporum ascendentium et descendentium, sit quasi quidam fluvius circularis communis aeri et aquae: nam quod aqua resolvitur in vaporem, ad aerem attinet, quod autem nubes in aquam condensantur, ad aquam. Cum ergo sol prope existit, iste fluvius vaporum ascendit sursum; cum autem elongatur sol, descendit deorsum; et hoc indesinenter fit secundum ordinem praedictum. Unde concludit quod forte antiqui dicentes Oceanum esse quendam fluvium circumdantem terram, occulte loquebantur de hoc fluvio, qui circulariter fluit circa terram, ut dictum est. 100. Thirdly [97], he shows how the above-mentioned transmutations bear an analogy to the first movent cause, i.e., to the circling of the sun. For a certain circling is discernible in the above-mentioned transmutations, as water is refined into vapors which are condensed into clouds, and the clouds into water, which falls to earth. He says therefore that this circular transmutation imitates the circular movement of the sun — for the sun is changed to diverse parts of the heaven (for example, to the north and to the south); and that cycle is completed in the fact that vapors ascend upwards and descend downwards. But we should understand this flow of ascending and descending vapors as a certain circular stream common to air and water: for the resolving of water into vapor pertains to the air, while the condensing of clouds into water pertains to the water. When, therefore, the sun is near, this river of vapors flows upward; when the sun is away, it flows downward; and this goes on without interruption in the order described. From this he concludes that perhaps the ancients, in speaking of Oceanus as a certain river surrounding the earth, were cryptically speaking of this river, which, as was said, flows circularly around the earth.
Deinde cum dicit: elevato autem humido etc., determinat de praedictis passionibus in speciali, ostendendo differentias earum adinvicem. Et dividitur in duas partes: 101. Then at [98] he discusses the foregoing passions in detail, by pointing out their mutual differences. And it is divided into two parts:

in prima determinat de generatione illorum quae manifestiorem habent causam;

in secunda de generatione grandinis, circa quam est maior difficultas, ibi: ipsa autem aqua et cetera.

In the first he determines about the generation of those phenomena whose cause is quite plain;

In the second about the generation of hail, concerning which there is greater difficulty (L. 15).

Circa primum duo facit. Primo determinat de pluviis: dicens quod cum humidum aqueum elevatur ex virtute calidi, et iterum fertur deorsum propter infrigidationem, secundum quasdam differentias, huiusmodi passionibus aeris diversa nomina imponuntur. Quia quando per modicas partes vapores inspissati in aquam cadunt, tunc dicuntur psecades, idest guttae, sicut aliquando contingit quod parvae guttae decidunt: quando vero secundum maiores partes decidunt guttae ex vaporibus generatae, vocatur pluvia. 102. About the first he does two things: first, he determines about rain [98] and says that when watery moisture is elevated through the power of heat and is again brought down on account of cooling, different names, based on varying characteristics, are given to these passions of air. For when the vapors condensed into water in small parts fall, then they are called "psecades," i.e., drops, as occasionally happens, when small drops fall; but when the drops of a larger size generated from the vapors fall, this is called "rain."
Secundo ibi: ex eo autem quod de die etc., determinat de rore et pruina. Et circa hoc tria facit. Primo determinat modum generationis eorum. Et dicit quod ros et pruina contingunt ex hoc quod de die, sole existente super terram, aliquid evaporat ex humido aqueo propter solis calorem; quod quidem evaporatum non multum suspenditur vel elevatur super terram, propter hoc quod ignis, idest calor elevans huiusmodi vaporem, est parvus in comparatione ad humorem aqueum qui elevatur. Et ita, cum de nocte infrigidatus fuerit aer, inspissatur ille vapor elevatus de die, et cadit in terram, et vocatur ros vel pruina: ut ita se habeat accessus solis et recessus secundum motum diurnum ad generationem roris et pruinae, secundum quod se habet ad generationem pluviae secundum motum proprium, secundum quod accedit et recedit in aestate et hieme. 103. Secondly [99], he determines about dew and frost. First, he determines the manner in which they are generated. And he says that they arise from the fact that, when the sun is above the earth in daytime, something evaporates from the watery moisture because of the sun's heat, but this evaporation is not suspended or raised very high above the earth, for the simple reason that the "fire," i.e., the heat raising this vapor, is slight in comparison with the watery moisture elevated. Consequently, when the air cools at night, the vapor elevated during the day condenses and falls to earth and is called "dew" or "frost." The approach and departure of the sun in its diurnal course has the same relation to the generation of dew and frost as, in the generation of rain, its proper motion has according as it approaches and departs in summer and winter.
Secundo ibi: pruina quidem etc., ostendit differentiam eorum: dicens quod pruina fit, quando vapor prius congelatur quam condensetur in aquam; et propter hoc fit in hieme et in hiemalibus locis, idest in frigidis locis. Sed ros fit, quando vapor inspissatur in aquam, et neque est tantus aestus quod vapor elevatus desiccetur, neque est tantum frigus quod vapor congeletur. Et ideo oportet quod sit aut in tempore aut in loco calido: quia ros semper fit in tempore temperato et in locis temperatis, sed pruina, sicut dictum est, fit in tempore et loco magis frigidis. Cum enim vapor sit calidior aqua, quia adhuc est in eo aliquid de calore elevante, maior frigiditas requiritur ad congelationem vaporis quam aquae; et sic pruina nunquam fit nisi in magno frigore. 104. Secondly [100], he points out their difference and says that frost occurs when the vapor is frozen before it is condensed into water: for this reason it occurs in winter and in "wintry," i.e., frigid, places. But dew occurs when the vapor is thickened into water and there is neither enough heat to dry out the vapor that has been raised, nor enough cold for the vapor to freeze. Hence dew must occur either during warm seasons or in warm places: because dew occurs always in temperate times or temperate places, but frost in times and places that are colder, as has been said. For since vapor is warmer than water (because some of the heat raising it is still in it) more cold is needed to freeze vapor than to freeze water: as a result, frost never occurs except where there is much cold.
Deinde cum dicit: fiunt autem ambo etc., ostendit qualiter existente aere disposito, fit ros et pruina. 105. Then [101] he shows the conditions of disposed air under which dew and frost occur.

Et primo ostendit hoc communiter quantum ad utrumque;

secundo specialiter de rore, ibi: fit autem ros ubique et cetera.

First, he shows this generally as to both, at 105;

Secondly, specially for dew, at 107.

Circa primum duo facit: About the first he does two things:

primo ostendit quod proponit;

secundo ponit quoddam signum praedictorum, ibi: signum autem et cetera.

First, he shows what he is proposing, at 105;

Secondly, he gives a sign of the aforesaid, at 106.

Dicit ergo primo quod tam ros quam pruina fiunt cum aer fuerit serenus absque nubibus et pluvia, et tranquillus absque vento. Quia si non sit serenus, non possunt elevari vapores de die, propter defectum caloris: si autem non fuerit tranquillitas, vento flante, non poterunt vapores condensari, ut generetur ros; nam ventus, commovendo aerem, impedit congregationem vaporum. He says therefore first [101], that both dew and frost occur when the air is clear, without clouds and rain, and calm, without wind. Because if it is not clear, vapors cannot be lifted up during the day due to the lack of sufficient heat: if it is not calm, but windy, the vapors could not be condensed to form dew — for the wind, in agitating the air, prevents the vapors from massing together.
Deinde cum dicit: signum autem etc., manifestat per signum quod supra posuerat de generatione roris et pruinae. Et dicit quod signum huius quod ros et pruina causentur ex hoc quod vapor non longe elevatur a terra, est hoc quod in montibus non fit pruina, cum tamen ibi magis videatur fieri propter loci frigiditatem. Huius ergo sunt duae causae. Una quidem, quia vapor ex quo generatur ros et pruina, elevatur ex locis infimis et humefactis, ex quibus multi vapores generantur et elevantur: unde caliditas quae eos elevavit, non potuit elevare eos ad multam altitudinem, quasi portans onus quod excedit suam virtutem; sed prope loca infima dimittit calor vapores, et cadit ros et pruina. Unde in montibus altis pruina esse non potest. Secunda autem causa est, quia sicut supra dictum est, aer superior excedens montes, fluit quasi tractus ex motu caeli; et ideo suo fluxu dissolvit huiusmodi adunationem vaporum, quae est causa roris et pruinae. Plus autem de motu requiritur ad multam materiam vaporosam disgregandam, quam disgregandam parvam: materia autem pluviae et nivis est multa, materia autem roris et pruinae est pauca simpliciter, licet sit multa in comparatione ad calorem parvum elevantem ipsam: unde in montibus altissimis, propter maiorem fluxum aeris, neque pluvia neque ros neque pruina cadit; in montibus autem non ita altis cadit pluvia et nix, propter minorem fluxum, non autem ros et pruina. 106. Then [102] he gives a sign to support what he posited earlier about generation of dew and frost. And he says that a sign of the fact that dew and frost are caused by the fact that vapor is not lifted far above the earth is that frost does not appear on mountains, whereas it would seem that, on account of the cold there present, it should appear there even more. There are two reasons for this: First, because the vapor from which dew and frost are generated is raised from low, moist, places, from which many vapors are generated and lifted up: hence the heat which elevates them, bearing, as it were, a burden too much for its power, cannot raise them to a very great height; hence, while still near the lowest places, the heat leaves the vapors, and dew and frost fall. That is why frost cannot form on high mountains. The second cause is that, as previously stated, the upper air above the mountains flows along, as though carried by the course of the heaven; and therefore, by its flowing it dissolves such gatherings of vapor that cause dew and frost. Now, more motion is needed for scattering large amounts of vaporous matter than small amounts: but the matter of rain and snow coalesces in large amounts, whereas the matter of dew and frost is, absolutely speaking, small, although it is large in relation to the small amount of heat elevating it: hence neither rain nor dew nor frost fall on the highest mountains, because of the greater flow of air; but on mountains that are not so lofty, rain and snow, but no dew or frost, fall, because of the lesser flow of air.
Deinde cum dicit: fit autem ros ubique etc., ostendit specialiter de rore quali dispositione fiat. Et circa hoc tria facit. Primo proponit veritatem: dicens quod ros fit in omnibus locis, flantibus Australibus ventis, non tamen ita validis quod impediant congregationem vaporum. Non autem fit flantibus borealibus ventis, nisi in regione Ponti, quae est frigidissima: ibi enim contrarie accidit, nam tempore boreali fit ros, non autem tempore Australi. 107. Then [103] he shows under what circumstances dew in particular occurs. About this he does three things: first, he proposes a truth and says that dew forms in all places with south winds that are not strong enough to prevent vapors from gathering. It does not form with the blowing of the north wind except in the region of Pontus, which is very cold: there the opposite takes place, for dew forms there with northerly weather but not with southerly weather.
Secundo ibi: causa autem similiter etc., assignat causam eius quod communiter accidit. Et dicit quod causa huius est similis ei quod dictum est: quia scilicet ros fit in tempore temperato, sed non fit in hieme, idest in tempore valde frigido. Et rationem similitudinis ostendit: quia Auster facit temperiem, sed Boreas facit hiemem et frigus, est enim frigidus; et ideo ex hieme, idest ex frigiditate, extinguit caliditatem exhalationis, ut scilicet non possint vapores elevari ad generationem roris. 108. Secondly [104], he assigns the cause of what generally happens and says that the cause of this is akin to what has been said: namely, that dew forms in temperate times but not in "winter," i.e., in very cold times. And he shows the point of similarity: the south wind brings mildness, but the north wind winter and cold, for it is a cold wind; and therefore, because of the "winter," i.e., because of the coldness, the warmth is extinguished from exhalations, and, as a result, the vapors cannot be elevated for dew to be formed.
Tertio ibi: in Ponto autem etc., assignat causam eius quod accidit in Ponto. Et est quod ibi, propter magnam frigiditatem, Auster non sufficit ad facere tantam temperiem quae sufficiat ad elevationem vaporis; et ideo tempore Australi ibi non fit ros. Sed Boreas, propter suam frigiditatem, congregat calidum quod est in locis humectis, antiperistasim faciens, idest cum quadam contrarietate circumstans calidum: cum enim frigidum circumstat calidum, si non omnino possit extinguere ipsum, congregat illud. Et sic ex congregatione calidi vigoratur effectus eius, et ideo magis resolvitur vapor. 109. Thirdly [105], he assigns the cause of what happens in Pontus. The reason is that, because of the great cold there, the south wind is unable to produce sufficient mildness for vapors to be elevated: therefore no dew forms there during the time of the south wind. But the north wind, because of its coldness, collects the warm matter existing in damp places, "making a kind of anti-surrounding," i.e., by surrounding the warm matter with a certain contrariety — for when cold matter surrounds warm matter, if the former cannot completely quench the latter, it concentrates it. Thus, by the concentration of the hot, its effect is strengthened — and, as a result, more vapor is resolved.
Et hoc non tantum in Ponto accidit, sed etiam in aliis locis frequenter videtur factum: quia putei magis vaporant flantibus ventis borealibus quam Australibus, propter calorem congregatum interius ex frigore circumstante. Sed tamen in aliis locis frigiditas Boreae extinguit caliditatem vaporum, antequam aliqua multitudo possit adunari ad generationem roris: sed quando fiunt venti Australes, non impeditur congregatio vaporum ut generetur ros. Sed in Ponto etiam aliquando propter Boream extinguitur calor vaporum, et impeditur eorum elevatio: sed aliquando, propter multitudinem frigoris, multum de calido includitur intra terram, et fit multa exhalatio vaporum; ita quod ad modicum tempus resistit frigiditati aeris, donec congregetur tantum quod sufficiat ad generationem roris. This occurs not only in Pontus but is frequently observed in other places: wells evaporate more with a north wind than with a south wind, because of the heat trapped in them by the surrounding cold. However, in other places the coldness of the north wind quenches the vapor's heat before any can be concentrated in amounts large enough to generate dew; but when there are south winds, they do not impede the accumulation of vapors needed for generating dew. Even in Pontus there are times when, because of the north wind, the heat of the vapors is quenched and, therefore, do not rise; but sometimes, because of the greatness of the cold, much warmth is enclosed within the earth and a large amount of vaporous exhalation forms, in such a way that, for a brief time, it resists the air's coldness, but only long enough for an amount sufficient for the generation of dew to be accumulated.

Lecture 15
On the place of the generation of hail and snow
Chapter 11
ἐκεῖθεν γὰρ τρία φοιτᾷ σώματα συνιστάμενα διὰ τὴν ψύξιν, ὕδωρ καὶ χιὼν καὶ χάλαζα. τούτων δὲ τὰ μὲν δύο ἀνάλογον καὶ διὰ τὰς αὐτὰς αἰτίας γίγνεται τοῖς κάτω, διαφέροντα τῷ μᾶλλον καὶ ἧττον καὶ πλήθει καὶ ὀλιγότητι χιὼν γὰρ καὶ πάχνη ταὐτόν, καὶ ὑετὸς καὶ δρόσος, ἀλλὰ τὸ μὲν πολὺ τὸ δ' ὀλίγον. ὁ μὲν γὰρ ὑετὸς ἐκ πολλῆς ἀτμίδος γίγνεται ψυχομένης τούτου δ' αἴτιον ὅ τε τόπος πολὺς καὶ ὁ χρόνος ὤν, ἐν ᾧ συλλέγεται καὶ ἐξ οὗ. τὸ δ' ὀλίγον ἡ δρόσος ἐφήμερος γὰρ ἡ σύστασις καὶ ὁ τόπος μικρός δηλοῖ τε ἥ τε γένεσις οὖσα ταχεῖα καὶ βραχὺ τὸ πλῆθος. ὁμοίως δὲ καὶ πάχνη καὶ χιών ὅταν γὰρ παγῇ τὸ νέφος, χιών ἐστιν, ὅταν δ' ἡ ἀτμίς, πάχνη. διὸ ἢ ὥρας ἢ χώρας ἐστὶν σημεῖον ψυχρᾶς οὐ γὰρ ἂν ἐπήγνυτο ἔτι πολλῆς ἐνούσης θερμότητος, εἰ μὴ ἐπεκράτει τὸ ψῦχος ἐν γὰρ τῷ νέφει ἔτι ἔνεστιν πολὺ θερμὸν τὸ ὑπόλοιπον τοῦ ἐξατμίσαντος ἐκ τῆς γῆς τὸ ὑγρὸν πυρός. χάλαζα δ' ἐκεῖ μὲν γίγνεται, ἐν δὲ τῷ πλησίον τῆς γῆς ἀτμίζοντι τοῦτ' ἐκλείπει καθάπερ γὰρ εἴπομεν, ὡς μὲν ἐκεῖ χιών, ἐνταῦθα γίγνεται πάχνη, ὡς δ' ἐκεῖ ὑετός, ἐνταῦθα δρόσος ὡς δ' ἐκεῖ χάλαζα, ἐνταῦθα οὐκ ἀνταποδίδωσι τὸ ὅμοιον. τὸ δ' αἴτιον εἰποῦσι περὶ χαλάζης ἔσται δῆλον. 106 From the latter there fall three bodies condensed by cold, namely rain, snow, hail. Two of these correspond to the phenomena on the lower level and are due to the same causes, differing from them only in degree and quantity. Snow and hoar-frost are one and the same thing, and so are rain and dew: only there is a great deal of the former and little of the latter. For rain is due to the cooling of a great amount of vapour, for the region from which and the time during which the vapour is collected are considerable. But of dew there is little: for the vapour collects for it in a single day and from a small area, as its quick formation and scanty quantity show. The relation of hoar-frost and snow is the same: when cloud freezes there is snow, when vapour freezes there is hoar-frost. Hence snow is a sign of a cold season or country. For a great deal of heat is still present and unless the cold were overpowering it the cloud would not freeze. For there still survives in it a great deal of the heat which caused the moisture to rise as vapour from the earth. Hail on the other hand is found in the upper region, but the corresponding phenomenon in the vaporous region near the earth is lacking. For, as we said, to snow in the upper region corresponds hoar-frost in the lower, and to rain in the upper region, dew in the lower. But there is nothing here to correspond to hail in the upper region. Why this is so will be clear when we have explained the nature of hail.
Chapter 12
δεῖ δὲ λαβεῖν ἅμα καὶ τὰ συμβαίνοντα περὶ τὴν γένεσιν αὐτῆς, τά τε μὴ πλανῶντα καὶ τὰ δοκοῦντ' εἶναι παράλογα. ἔστι μὲν γὰρ ἡ χάλαζα κρύσταλλος, πήγνυται δὲ τὸ ὕδωρ τοῦ χειμῶνος αἱ δὲ χάλαζαι γίγνονται ἔαρος μὲν (348a.) καὶ μετοπώρου μάλιστα, εἶτα δὲ καὶ τῆς ὀπώρας, χειμῶνος δ' ὀλιγάκις, καὶ ὅταν ἧττον ᾖ ψῦχος. καὶ ὅλως δὲ γίγνονται χάλαζαι μὲν ἐν τοῖς εὐδιεινοτέροις τόποις, αἱ δὲ χιόνες ἐν τοῖς ψυχροτέροις. 107 But we must go on to collect the facts bearing on the origin of it, both those which raise no difficulties and those which seem paradoxical. Hail is ice, and water freezes in winter; yet hailstorms occur chiefly in spring and autumn and less often in the late summer, but rarely in winter and then only when the cold is less intense. And in general hailstorms occur in warmer, and snow in colder places.
ἄτοπον δὲ καὶ τὸ πήγνυσθαι ὕδωρ ἐν τῷ ἄνω τόπῳ οὔτε γὰρ παγῆναι δυνατὸν πρὶν γενέσθαι ὕδωρ, οὔτε τὸ ὕδωρ οὐδένα χρόνον οἷόν τε μένειν μετέωρον ὄν. 108 Again, there is a difficulty about water freezing in the upper region. It cannot have frozen before becoming water: and water cannot remain suspended in the air for any space of time.
ἀλλὰ μὴν οὐδ' ὥσπερ αἱ ψακάδες ἄνω μὲν ὀχοῦνται διὰ μικρότητα, ἐνδιατρίψασαι δ' ἐπὶ τοῦ ἀέρος, ὥσπερ καὶ ἐπὶ τοῦ ὕδατος γῆ καὶ χρυσὸς διὰ μικρομέρειαν πολλάκις ἐπιπλέουσιν, οὕτως ἐπὶ τοῦ ἀέρος τὸ ὕδωρ, συνελθόντων δὲ πολλῶν μικρῶν μεγάλαι καταφέρονται ψακάδες 109 Nor can we say that the case is like that of particles of moisture which are carried up owing to their small size and rest on the iar (the water swimming on the air just as small particles of earth and gold often swim on water). In that case large drops are formed by the union of many small, and so fall down.
τοῦτο γὰρ οὐκ ἐνδέχεται γενέσθαι ἐπὶ τῆς χαλάζης οὐ γὰρ συμφύεται τὰ πεπηγότα ὥσπερ τὰ ὑγρά. δῆλον οὖν ὅτι ἄνω τοσοῦτον ὕδωρ ἔμεινεν οὐ γὰρ ἂν ἐπάγη τοσοῦτον. 110 This cannot take place in the case of hail, since solid bodies cannot coalesce like liquid ones. Clearly then drops of that size were suspended in the air or else they could not have been so large when frozen.
τοῖς μὲν οὖν δοκεῖ τοῦ πάθους αἴτιον εἶναι τούτου καὶ τῆς γενέσεως, ὅταν ἀπωσθῇ τὸ νέφος εἰς τὸν ἄνω τόπον μᾶλλον ὄντα ψυχρὸν διὰ τὸ λήγειν ἐκεῖ τὰς ἀπὸ τῆς γῆς τῶν ἀκτίνων ἀνακλάσεις, ἐλθὸν δ' ἐκεῖ πήγνυσθαι τὸ ὕδωρ διὸ καὶ θέρους μᾶλλον καὶ ἐν ταῖς ἀλεειναῖς χώραις γίγνεσθαι τὰς χαλάζας, ὅτι ἐπὶ πλέον τὸ θερμὸν ἀνωθεῖ ἀπὸ τῆς γῆς τὰς νεφέλας. 111 Some think that the cause and origin of hail is this. The cloud is thrust up into the upper atmosphere, which is colder because the reflection of the sun's rays from the earth ceases there, and upon its arrival there the water freezes. They think that this explains why hailstorms are commoner in summer and in warm countries; the heat is greater and it thrusts the clouds further up from the earth.
συμβαίνει δ' ἐν τοῖς σφόδρα ὑψηλοῖς ἥκιστα γίγνεσθαι χάλαζαν καίτοι ἔδει, ὥσπερ καὶ τὴν χιόνα ὁρῶμεν ἐπὶ τοῖς ὑψηλοῖς μάλιστα γιγνομένην. 112 But the fact is that hail does not occur at all at a great height: yet it ought to do so, on their theory, just as we see that snow falls most on high mountains.
ἔτι δὲ πολλάκις ὦπται νέφη φερόμενα σὺν ψόφῳ πολλῷ παρ' αὐτὴν τὴν γῆν, ὥστε φοβερὸν εἶναι τοῖς ἀκούουσιν καὶ ὁρῶσιν ὡς ἐσομένου τινὸς μείζονος. ὁτὲ δὲ καὶ ἄνευ ψόφου τοιούτων ὀφθέντων νεφῶν χάλαζα γίγνεται πολλὴ καὶ τὸ μέγεθος ἄπιστος, καὶ τοῖς σχήμασιν οὐ στρογγύλη, διὰ τὸ μὴ πολὺν χρόνον γίγνεσθαι τὴν φορὰν αὐτῆς ὡς πλησίον τῆς πήξεως γενομένης τῆς γῆς, ἀλλ' οὐχ ὥσπερ ἐκεῖνοί φασιν. 113 Again clouds have often been observed moving with a great noise close to the earth, terrifying those who heard and saw them as portents of some catastrophe. Sometimes, too, when such clouds have been seen, without any noise, there follows a violent hailstorm, and the stones are of incredible size, and angular in shape. This shows that they have not been falling for long and that they were frozen near to the earth, and not as that theory would have it.
ἀλλὰ μὴν ἀναγκαῖον ὑπὸ τοῦ μάλιστ' αἰτίου τῆς πήξεως μεγάλας γίγνεσθαι χαλάζας κρύσταλλος γὰρ ἡ χάλαζα, καὶ τοῦτο παντὶ δῆλον. μεγάλαι δ' εἰσὶν αἱ τοῖς σχήμασιν μὴ στρογγύλαι. τοῦτο δ' ἐστὶ σημεῖον τοῦ παγῆναι πλησίον τῆς γῆς αἱ γὰρ φερόμεναι πόρρωθεν διὰ τὸ φέρεσθαι μακρὰν περιθραυόμεναι γίγνονται τό τε σχῆμα περιφερεῖς καὶ τὸ μέγεθος ἐλάττους. ὅτι μὲν (348b.) οὖν οὐ τῷ ἀπωθεῖσθαι εἰς τὸν ἄνω τόπον τὸν ψυχρὸν ἡ πῆξις συμβαίνει, δῆλον 114 Moreover, where the hailstones are large, the cause of their freezing must be present in the highest degree: for hail is ice as every one can see. Now those hailstones are large which are angular in shape. And this shows that they froze close to the earth, for those that fall far are worn away by the length of their fall and become round and smaller in size. It clearly follows that the congelation does not take place because the cloud is thrust up into the cold upper region.
ἀλλ' ἐπειδὴ ὁρῶμεν ὅτι γίγνεται ἀντιπερίστασις τῷ θερμῷ καὶ ψυχρῷ ἀλλήλοις (διὸ ἔν τε ταῖς ἀλέαις ψυχρὰ τὰ κάτω τῆς γῆς καὶ ἀλεεινὰ ἐν τοῖς πάγοις), τοῦτο δεῖ νομίζειν καὶ ἐν τῷ ἄνω γίγνεσθαι τόπῳ, ὥστ' ἐν ταῖς ἀλεεινοτέραις ὥραις ἀντιπεριιστάμενον εἴσω τὸ ψυχρὸν διὰ τὴν κύκλῳ θερμότητα ὁτὲ μὲν ταχὺ ὕδωρ ἐκ νέφους ποιεῖ διὸ καὶ αἱ ψακάδες πολὺ μείζους ἐν ταῖς ἀλεειναῖς γίγνονται ἡμέραις ἢ ἐν τῷ χειμῶνι, καὶ ὕδατα λαβρότερα λαβρότερα μὲν γὰρ λέγεται ὅταν ἀθροώτερα, ἀθροώτερα δὲ διὰ τὸ τάχος τῆς πυκνώσεως. (τοῦτο δὲ γίγνεται αὐτὸ τοὐναντίον ἢ ὡς Ἀναξαγόρας λέγει ὁ μὲν γὰρ ὅταν εἰς τὸν ψυχρὸν ἀέρα ἐπανέλθῃ φησὶ τοῦτο πάσχειν, ἡμεῖς δ' ὅταν εἰς τὸν θερμὸν κατέλθῃ, καὶ μάλιστα ὅταν μάλιστα.) ὅταν δ' ἔτι μᾶλλον ἀντιπεριστῇ ἐντὸς τὸ ψυχρὸν ὑπὸ τοῦ ἔξω θερμοῦ, ὕδωρ ποιῆσαν ἔπηξεν καὶ γίγνεται χάλαζα. 115 Now we see that warm and cold react upon one another by recoil. Hence in warm weather the lower parts of the earth are cold and in a frost they are warm. The same thing, we must suppose, happens in the air, so that in the warmer seasons the cold is concentrated by the surrounding heat and causes the cloud to go over into water suddenly. (For this reason rain-drops are much larger on warm days than in winter, and showers more violent. A shower is said to be more violent in proportion as the water comes down in a body, and this happens when the condensation takes place quickly,—though this is just the opposite of what Anaxagoras says. He says that this happens when the cloud has risen into the cold air; whereas we say that it happens when the cloud has descended into the warm air, and that the more the further the cloud has descended). But when the cold has been concentrated within still more by the outer heat, it freezes the water it has formed and there is hail.
συμβαίνει δὲ τοῦτο ὅταν θᾶττον ᾖ ἡ πῆξις ἢ ἡ τοῦ ὕδατος φορὰ ἡ κάτω εἰ γὰρ φέρεται μὲν ἐν τοσῷδε χρόνῳ, ἡ δὲ ψυχρότης σφοδρὰ οὖσα ἐν ἐλάττονι ἔπηξεν, οὐδὲν κωλύει μετέωρον παγῆναι, ἐὰν ἡ πῆξις ἐν ἐλάττονι γίγνηται χρόνῳ τῆς κάτω φορᾶς. καὶ ὅσῳ δ' ἂν ἐγγύτερον καὶ ἀθροωτέρα γένηται ἡ πῆξις, τά τε ὕδατα λαβρότερα γίγνεται καὶ αἱ ψακάδες καὶ αἱ χάλαζαι μείζους διὰ τὸ βραχὺν φέρεσθαι τόπον. καὶ οὐ πυκναὶ αἱ ψακάδες αἱ μεγάλαι πίπτουσιν διὰ τὴν αὐτὴν αἰτίαν. 116 We get hail when the process of freezing is quicker than the descent of the water. For if the water falls in a certain time and the cold is sufficient to freeze it in less, there is no difficulty about its having frozen in the air, provided that the freezing takes place in a shorter time than its fall. The nearer to the earth, and the more suddenly, this process takes place, the more violent is the rain that results and the larger the raindrops and the hailstones because of the shortness of their fall. For the same reason large raindrops do not fall thickly.
ἧττον δὲ τοῦ θέρους γίγνεται ἢ ἔαρος καὶ μετοπώρου, μᾶλλον μέντοι ἢ χειμῶνος, ὅτι ξηρότερος ὁ ἀὴρ τοῦ θέρους ἐν δὲ τῷ ἔαρι ἔτι ὑγρός, ἐν δὲ τῷ μετοπώρῳ ἤδη ὑγραίνεται. γίγνονται δέ ποτε, καθάπερ εἴρηται, καὶ τῆς ὀπώρας χάλαζαι διὰ τὴν αὐτὴν αἰτίαν. 117 Hail is rarer in summer than in spring and autumn, though commoner than in winter, because the air is drier in summer, whereas in spring it is still moist, and in autumn it is beginning to grow moist. It is for the same reason that hailstorms sometimes occur in the late summer as we have said.
συμβάλλεται δ' ἔτι πρὸς τὴν ταχυτῆτα τῆς πήξεως καὶ τὸ προτεθερμάνθαι τὸ ὕδωρ θᾶττον γὰρ ψύχεται. διὸ πολλοὶ ὅταν τὸ ὕδωρ ψῦξαι ταχὺ βουληθῶσιν, εἰς τὸν ἥλιον τιθέασι πρῶτον, καὶ οἱ περὶ τὸν Πόντον ὅταν ἐπὶ τοῦ κρυστάλλου σκηνοποιῶνται πρὸς τὰς τῶν ἰχθύων θήρας (θηρεύουσι γὰρ διακόπτοντες τὸν κρύσταλλον), ὕδωρ θερμὸν (349a.) περιχέουσι τοῖς καλάμοις διὰ τὸ θᾶττον πήγνυσθαι χρῶνται γὰρ τῷ κρυστάλλῳ ὥσπερ τῷ μολύβδῳ, ἵν' ἠρεμῶσιν οἱ κάλαμοι. θερμὸν δὲ γίγνεται ταχὺ τὸ συνιστάμενον ὕδωρ ἔν τε ταῖς χώραις καὶ ταῖς ὥραις ταῖς ἀλεειναῖς. γίγνεται δὲ καὶ περὶ τὴν Ἀραβίαν καὶ τὴν Αἰθιοπίαν τοῦ θέρους τὰ ὕδατα καὶ οὐ τοῦ χειμῶνος, καὶ ταῦτα ῥαγδαῖα, καὶ τῆς αὐτῆς ἡμέρας πολλάκις, διὰ τὴν αὐτὴν αἰτίαν ταχὺ γὰρ ψύχεται τῇ ἀντιπεριστάσει, ἣ γίγνεται διὰ τὸ ἀλεεινὴν εἶναι τὴν χώραν ἰσχυρῶς. 118 The fact that the water has previously been warmed contributes to its freezing quickly: for so it cools sooner. Hence many people, when they want to cool hot water quickly, begin by putting it in the sun. So the inhabitants of Pontus when they encamp on the ice to fish (they cut a hole in the ice and then fish) pour warm water round their reeds that it may freeze the quicker, for they use the ice like lead to fix the reeds. Now it is in hot countries and seasons that the water which forms soon grows warm. It is for the same reason that rain falls in summer and not in winter in Arabia and Ethiopia too, and that in torrents and repeatedly on the same day. For the concentration or recoil due to the extreme heat of the country cools the clouds quickly.
περὶ μὲν οὖν ὑετοῦ καὶ δρόσου καὶ νιφετοῦ καὶ πάχνης καὶ χαλάζης, διὰ τίν' αἰτίαν γίγνεται καὶ τίς ἡ φύσις αὐτῶν ἐστιν, εἰρήσθω τοσαῦτα. 119 So much for an account of the nature and causes of rain, dew, snow, hoar-frost, and hail.
Postquam philosophus determinavit de generatione pluviae, roris et pruinae, hic incipit determinare de generatione grandinis. Et circa hoc tria facit: 110. After determining about the generation of rain, dew and frost, the Philosopher here begins to determine about the formation of hail. About this he does three things:

primo ostendit locum generationis grandinis;

secundo enumerat quaedam accidentia circa grandinem, quae faciunt difficultatem circa generationem ipsius, ibi: oportet autem accipere etc.;

tertio assignat causam generationis eius, ibi: his quidem igitur et cetera.

First, he shows where hail is generated;

Secondly, he enumerates certain phenomena accompanying hail that raise a difficulty about its formation, at 111;

Thirdly, he assigns the cause of its generation, at 115.

Dicit ergo primo quod, licet vapor congeletur in hoc inferiori aere vicino terrae, tamen aqua non coagulatur hic ad generationem grandinis, sicut coagulatur in loco nubium. Ex illo enim loco veniunt tria corpora inspissata propter infrigidationem, scilicet aqua pluviae et nix et grando. Sed duobus horum corporum quaedam proportionalia fiunt in loco inferiori vicino terrae, quae ex eisdem causis generantur, sed differunt a pluvia et nive secundum magis et minus, prout scilicet citius vel tardius fit generatio, et secundum multitudinem et paucitatem. He says therefore first [106], that although vapor freezes in this lower air near the earth, yet water does not coagulate here to form hail as it coagulates in the region of the clouds. For three bodies condensed by cold come from that region: namely, rain water, snow and hail. But in the case of two of these bodies, certain proportionate things take place in the lower region near the earth, and which are generated from the same causes, but differ from rain and snow according to more and less, depending, namely, on whether they are produced more quickly or more slowly, and on largeness and smallness [of amount].
Nix enim et pruina proportionaliter sunt idem, et similiter pluvia et ros: sed differunt secundum multum et paucum. Quia pluvia fit ex multo vapore infrigidato: huius autem multitudinis causa est et locus magnus et spatiosus, et multum tempus in quo vapor adunatur et colligitur, et multus etiam locus ex quo colligitur; quia enim in alto generantur pluviae, ex multis partibus illuc concurrunt vapores. Ros autem habet paucum de vapore, quia tempus in quo colligitur est paucum (consistentia enim illius vaporis est ephemeros, idest unius diei), et locus in quo congregatur parvus est, quia congregatur in propinquo terrae: et hoc manifestum fit per hoc quod generatio roris est velox, et multitudo eius est parva. Et sicut se habet de rore et pluvia, ita se habet de nive et pruina: quando enim tota nubes congelatur, fit nix; quando vero aliquis parvus vapor circa terram congelatur, tunc fit pruina. Et ideo utrumque eorum est signum temporis aut regionis frigidae: quia cum in vapore et nube adhuc sit aliquid de caliditate, non congelaretur nisi esset magnum frigus supervincens caliditatem ipsam; quia in nube adhuc multum residuum est de calore qui fecit evaporare humidum aqueum a terra, in vapore autem adhuc magis. Sic ergo, sicut pluvia et nix fiunt superius, ita ros et pruina inferius. Sed tamen, licet grando fiat superius, non convenit ei proportionale inferius: et huius causa erit manifesta, cum exposita fuerit causa generationis grandinis. For snow and frost are proportionately the same, and likewise rain and dew: they differ according to abundance and scarcity. For rain comes to be from the cooling of an abundance of vapor — the cause of this abundance being a large and spacious region and a long time in which the vapor is being united and collected, and also a large place from which it is collected. For, since rains are generated on high, vapors collect there from many regions. Dew, on the other hand, has little vapor, because the time is short during which it is collected (for the consistency of that vapor is "ephemeral," i.e., of a single day), and the region is small in which it is collected, for it is collected close to the earth — and this becomes plain fog from the fact that the generating of dew is swift and its amount is small. And as it is with dew and rain, so with snow and frost: for when an entire cloud is frozen, snow comes to be; but when some small vapor near the earth freezes, frost comes to be. Therefore, both of them are a sign of cold weather or of a cold region — for, since some heat still abides in both the vapor and the cloud, they would not freeze, unless there were present a vast coldness overwhelming that heat: there being in the cloud still a large residue of the heat which made the watery moisture evaporate from the earth, and in the vapor still more. Thus, as rain and snow come to be in the upper region, so dew and frost in the lower. But although hail comes to be in the upper region, nothing below corresponds to it: the reason for this will be plain, when the cause of the generation of hail is explained.
Deinde cum dicit: oportet autem accipere etc., proponit quaedam accidentia quae accidunt circa grandinem, et faciunt difficultatem circa generationem ipsius. 111. Then [107] he proposes certain phenomena that occur with respect to hail and create a difficulty as to its generation;

Et proponit duas difficultates circa generationem grandinis:

secundam ponit ibi: inconveniens autem et cetera.

And he proposes two difficulties with respect to generation of hail;

The second one is mentioned at 112.

Dicit ergo primo quod oportet accipere ea quae accidunt circa generationem grandinis, quae putantur esse rationabilia, et non sunt falsa. Et primo proponit quod grando est sicut crystallus quidam, idest aqua vehementer congelata: et proponit iterum quod aqua maxime congelatur in hieme: ex quibus videtur sequi quod grando maxime fiat in hieme. Sed contrarium videtur accidere: quia grandines maxime fiunt in vere et in autumno; et post hoc, tempore fructuum, idest in aestate et circa principium autumni; minus autem in hieme, et tunc quando fuerit minus frigus hiemis. Et universaliter grandines fiunt in locis magis temperatis: nives autem in frigidioribus locis et temporibus. Unde et grandines, in quibus apparet maior congelatio, magis deberent fieri locis et temporibus frigidis. He says therefore first [107], that with respect to the generation of hail we must consider the facts which are thought to be reasonable, and not false. And first he proposes that hail is, as it were, "crystal," i.e., water solidly frozen; he further proposes that water freezes especially in winter. But the contrary is seen to happen: for hailstorms occur mainly in spring and autumn; and after this, during the time of fruit, i.e., in summer and around the onset of autumn; but less often in winter, and, in that case, when the cold of winter has been less. Generally speaking, hail occurs in more temperate places; snow in colder places and times. From all this it would seem that hail, in which a larger amount of freezing is involved, ought rather to occur in places and times that are cold.
Deinde cum dicit: inconveniens autem etc., ponit secundam difficultatem. Et circa hoc tria facit. Primo ponit difficultatem. Et dicit quod inconveniens videtur quod aqua congeletur superius: quia non potest congelari antequam sit facta; neque postquam est facta, remanere elevata, quoniam statim cadit. Unde non videtur quod possit dari tempus in quo congeletur ad generationem grandinis. 112. Then at [108] he presents a second difficulty, about which he does three things. First, he presents the difficulty and says that it appears inconsistent that water should freeze on high — for it cannot freeze before it is formed, nor after it is formed, can it remain aloft, since it falls immediately. Hence it does not appear that there can be time for it to freeze and generate hail.
Secundo ibi: at vero neque quemadmodum etc., ponit quandam apparentem solutionem huius difficultatis. Posset enim aliquis dicere quod aqua, divisa in partes minimas, remanet in aere quasi ei commixta; et non cadit statim, sed immoratur in aere. Et per hunc modum accidit quando cadunt psecades, de quibus supra dictum est. Et simile est etiam de terra respectu aquae, quae ita se habet ad terram sicut aer ad aquam: frequenter enim aurum vel terra supernatat aquae propter parvitatem partium; sed si congregarentur illae partes terrae vel auri, caderent sub aqua. Unde, congregatis parvis partibus aquae quae resident in aere, fiunt magnae guttae, et sic deorsum feruntur psecades. Et ita posset aliquis dicere non esse inconveniens quod aqua insidens aeri congelaretur ad generationem grandinis. 113. Secondly, he gives an apparent solution of this difficulty [109]. For one could say that the water, separated into minimal parts, remains in the air as though mingled with it, and does not fall at once, but abides in the air. This is what happens when "psecades" [droplets] fall, about which we spoke earlier. And a like thing is true of earth in respect to water, which is to earth, as air is to water: for often gold or earth float on water because of the minuteness of their particles; but if those particles of earth or gold coalesced, they would fall to the bottom of the water. Hence as a result of the small particles that abide in the air congregating, large drops are formed and, in this way, the drops are brought down. In like manner, one could say that it is not impossible for water permeating the air to freeze and form hail.
Tertio ibi: hoc enim non contingit etc., excludit dictam solutionem: dicens quod non contingit fieri in grandine, sicut contingit in psecadibus. Quia partes aquae congelatae, si essent parvae, non possent uniri ut facerent aliquod magnum, sicut est grando, sicut continuantur partes aquae humidae existentis: quia duriora, ut sunt congelata, non ita adunantur sicut humidiora. Unde oporteret quod tanta aqua quanta est magnitudo grandinis, sursum maneret in aere non cadens: quod patet, quia non esset tanta post congelationem, si non fuisset tanta ante congelationem; ex multis enim parvis non possunt fieri multa magna continua. Sed quod tanta aqua sursum maneat non cadens, videtur impossibile. 114. Thirdly [110], he rejects this solution and says that what happens to occur in droplets does not occur in the case of hail. For bits of frozen water, if small, could not consolidate to form something large like hailstones in the way that the parts of water, as moist, coalesce: for hard objects, such as ice, do not unite the way more moist things do. Hence a quantity of water equal to the size of the hailstone would have had to be hanging above in the air without falling: this is evident, for it could not be the size it is after freezing, if it had not been that size before freezing — since from many small things cannot be formed many large continua. But that such an amount of water should remain above without falling seems impossible.
Deinde cum dicit: his quidem igitur etc., assignat causam generationis grandinis. 115. Then [111] he assigns the cause of the generation of hail.

Et primo ponit opinionem aliorum;

secundo opinionem propriam, ibi: sed quoniam videmus et cetera.

First, he presents the opinions of others, at 115;

Secondly, his own opinion, at 119.

Circa primum duo facit. Primo proponit opinionem aliorum. Et dicit quod quibusdam videtur quod, cum nubes ex magno calore fuerit impulsa in locum superiorem, qui est valde frigidus ex eo quod ibi desinunt radii refracti a terra, aqua veniens ibi coagulatur, propter frigiditatem loci. Et ideo in aestate et in regionibus calidis fiunt grandines, quia magnus calor multum impellit nubes in superiorem locum sursum longe a terra. About the first he does two things: first, he presents the opinions of others [111] and says that it seems to some that when a large quantity of heat pushed a cloud into the upper region, which is very cold because the rays reflected from the earth do not reach there, the water arriving there is frozen on account of the region's being cold. And therefore the reason why hail occurs during the summer and in warm regions is that vast heat greatly pushes clouds into the upper region far from earth.
Secundo ibi: accidit autem etc., impugnat praedictam positionem tribus rationibus. Quarum prima est, quod videmus in altis montibus non fieri grandines: quod tamen oportebat, si per elevationem vaporis in locum multum altum generarentur grandines; sicut etiam videmus in montibus altis fieri nives, quae generantur in alto. 116. Secondly [112] he attacks this position on three scores. First, we see that hail does not occur on lofty mountains — but it should, if hail is formed by vapor lifted into very high places, just as we see snow, which is generated on high, on lofty mountains.
Secundam rationem ponit ibi: adhuc autem saepe et cetera. Et dicit quod saepe visae sunt nubes quae feruntur prope terram cum multo sono, ita ut quidam audientes cadentes terreantur, ac si aliquod maius futurum portendatur. Aliquando etiam, talibus nubibus visis prope terram sine sono, fit multa grando, incredibilis magnitudinis et figurae non rotundae. Hoc autem, scilicet quod grando non sit figurae rotundae et quod sit magnae quantitatis, accidit ex hoc quod congelatio grandinis est facta prope terram, et ideo parvo tempore fit motus ipsius: quia si multo tempore fieret, deminuta fuisset quantitas grandinis, et figura fuisset facta rotunda, motu dissolvente praecipue partes angulares, fortius dividentes aerem et magis ei resistentes. Non ergo verum est quod generatio grandinis fit multum longe a terra. 117. He gives the second argument [113] and says that clouds are often seen moving with a great noise close to the earth so that some people hearing it fall down in terror, as though it augured a great prodigy. At other times, when such clouds are seen near the earth without any noise, a great hailstorm occurs, with hailstones of incredible size and non-round shape. Now, these phenomena, namely, that the hail is not round in shape and that the stones are large, are due to the fact that the freezing of the hail took place near the earth; consequently its fall is of short duration — for if it had fallen a long time, the size of the hail would have been reduced and the shape rounded, because the descending motion would especially have dissolved the angled edges cleaving the air very strongly and offering it greater resistance. Therefore, it is not true that hail is generated very far from the earth.
Tertiam rationem ponit ibi: at vero necessarium et cetera. Et dicit quod necesse est quod magnitudo grandinis contingat ex fortitudine causae coagulationis grandinis: quia grando est quoddam congelatum sicut crystallus, ut est cuilibet manifestum. Sed magnitudo grandinis maior est in grandinibus quae non sunt rotundae: ex quo potest concludi quod grandines quae non sunt figurae rotundae, habeant fortem causam congelationis. Sed hoc quod grando non sit figurae rotundae, est signum quod sit congelata prope terram: quia si venirent de longe, circumquaque essent attritae, propter motum a longinquo, et sic essent figurae rotundae et magnitudine minores. Unde concludit quod coagulatio grandinis non accidit propter hoc quod vapores propellantur in locum frigidum supremum, multum remotum a terra. 118. He gives the third argument [114] and says that it is necessary that the size of the hail be due to the vigor of the cause freezing it: because hail is something congealed after the manner of crystal, as everyone can see. But the size of hail is greater when the stones are not round; from which it can be concluded that hailstones which are not round have vigorous cause of their freezing. But the very fact that the stone is not round is a sign that it froze close to the earth; because if the stones came from a great distance, their surface would have been worn down all over because of motion from a distance, and thus they would be round in shape and smaller in size. Hence he concludes that the freezing of hail is not due to vapors being pushed up into a highest cold region far from the earth.
Deinde cum dicit: sed quoniam videmus etc., assignat causam generationis grandinis. 119. Then [115] he assigns the cause of the generation of hail.

In quo primo excludit unam difficultatem superius motam;

secundo excludit aliam, ibi: accidit autem hoc et cetera.

First, he excludes one difficulty raised earlier;

Secondly, he excludes another one, at 120.

Dicit ergo primo quod per experimentum videmus quod calidum et frigidum sua contrarietate circumstant se invicem et aggregant. Et hoc manifestum est in terra. Nam in aestu interiora terrae sunt frigida, propter hoc quod caliditas aeris frigiditatem terrae circumstat; unde congregatur interius. E converso autem tempore frigoris interiora terrae sunt calida, propter hoc quod frigus concludit interius calorem qui erat in terra. Et inde est quod aqua fontium in aestate est frigida, et in hieme calida. Et hoc oportet putare fieri etiam in superiori loco. Unde in tempore calido frigidum, contrarietate calidi circumstantis inclusum, vehementius operatur: unde aliquando valde cito ex nube facit aquam. Et propter hoc multo maiores guttae fiunt in calidis diebus quam in hieme, et aquae pluviae fiunt labroterae, idest violentiores: quae quidem magnitudo et violentia accidunt ex eo quod quasi subito simul tota descendit pluvia, quod accidit propter celeritatem congelationis. He says therefore first [115] that from frequent experience we observe that the hot and the cold being contrary surround each other and cause gathering. And this is evident in the case of the earth. For in the hot weather the interior of the earth is cold, due to the fact that the heat of the air surrounds earth's coldness; hence it congregates together within. On the other hand, when it is cold, the interior of the earth is warm, because the cold encloses inside the warmth which was in the earth. That is why in summer the water from fountains is cool but warm in winter. The same thing must be supposed to take place in the upper region also. Therefore, when the weather is warm, the cold, shut in by the contrariety of the warmth surrounding, acts with greater force — as a result, the coldness sometimes can form water very quickly from a cloud. And, for this reason, much larger drops are formed on hot days than in winter, and the rains are '"labroterae," i.e., more violent. The size and violence are due to the fact that a whole sheet of rain descends very suddenly, which is due to the rapidity of condensation.
Et sic contrarium accidit ei quod dixit Anaxagoras. Dicebat enim hoc accidere, quando vapor ex quo generatur pluvia, ascendit in aerem valde frigidum: sed nos e converso dicimus quod hoc accidit, cum vapor descendit in aerem calidum; et tanto magis, quanto in magis calidum. Sic igitur ex calido circumstante frigidum et congregante ipsum, fiunt magnae guttae pluviarum et violentae. Sed cum frigidum magis congregatur conclusum ab exteriori calido, non solum subito condensantur nubes in aquam, sed ulterius aqua congelatur ex vehementi virtute frigidi inclusi, et sic fit grando. Unde patet solutio primae difficultatis: quare scilicet aqua congelatur in grandinem magis tempore aestatis quam hiemis. Therefore, what happens is the very contrary of Anaxagoras' theory, which held that this happens when the vapor, from which rain forms, rises into air which is very cold; but we, on the contrary, maintain that this happens when the vapor descends into warm air — and so much the more so according as the warmth is greater. Therefore, from the hot which surrounds and gathers together the cold, are due the large drops and the violence of the rain. But when the cold is still more gathered together as a result of being surrounded by an external warmth, not only are the clouds condensed into water suddenly but what is more, the water is frozen by the vehement power of the trapped coldness: then hail is formed. From this is plain the solution to the first difficulty: namely, why is water congealed into hail in warm weather more than in winter?
Deinde cum dicit: accidit autem hoc etc., solvit secundam difficultatem. Et circa hoc tria facit: 120. Then [1163 he solves the second difficulty. About this he does three things:

primo solvit difficultatem;

secundo assignat rationem de tempore generationis grandinis, ibi: minus autem aestate etc.;

tertio ponit quoddam conferens ad celeritatem generationis grandinis, ibi: confert autem et cetera.

First, he solves the difficulty;

Secondly, he gives an explanation for the season in which hail is formed, 121.

Thirdly, he lays down something that contributes to the speed with which hail is formed, at 122.

Fuit autem secunda difficultas ex hoc quod non videbatur posse dari tempus in quo superius aqua congelaretur in grandinem; quia statim dum aqua generatur, cadit; et antequam generetur, congelari non potest. Ad solvendam igitur hanc difficultatem, dicit quod generatio grandinis accidit, quando est velocior aquae congelatio, propter virtutem frigoris congregati, quam motus aquae pluviae deorsum. The second difficulty arose from the fact that there did not seem to be able to be any time for the water on high to freeze into hail — for as soon as water is formed, it falls, and it cannot freeze before it has formed. To solve this difficulty, therefore, he says [116] that the generation of hail occurs when the freezing of water is more rapid (on account of the vigor of the cold gathered together) than the downward motion of the water.
Et quod hoc sit possibile, ostendit. Cum enim omnis motus localis sit in tempore, manifestum est quod in aliquo determinato tempore aqua pluviae fertur deorsum; contingit autem quod in minori tempore frigiditas, propter suam vehementiam, congelat aquam, quam sit tempus descensus eius; unde nihil prohibet si congelatio fiat in minori tempore quam motus deorsum aquae, si frigidum existat fortius et vehemens. Et hinc est quod quanto propinquius nobis fit generatio aquae vel grandinis, tanto magis subito congeletur, calido existente fortiori prope terram, et vehementius expellente et concludente frigidum. Et ideo oportet quod et aquae pluviae fiant violentiores, et tam guttae pluviarum quam grandinum sint maiores, propter hoc quod per minus spatium feruntur, et minus ex eis dissolvitur. Illae autem guttae quae cadunt magnae, non sunt crebrae, propter eandem causam: quia enim subito et simul congelantur in magnas, non in multas partes dividuntur, et subito etiam cadunt; sicque materia pluviae et grandinis non tam spissim cadit. That this is possible he now shows. For since every instance of local motion is in time, it is plain that the rain water is traveling downward for some definite period of time; but it happens that the coldness, because of its vigor, freezes the water in less time than the time of descent. Hence there is nothing to prevent the freezing from occurring in less time than it takes the water to descend, if the cold is very vigorous and intense. This is why, the nearer to us the generation of water or hail takes place, the faster it freezes, since the heat is stronger near the earth and more vigorously expels and encloses the cold. In these circumstances the water of the rain must become more violent, and both the drops of rain and the hailstones larger, because they travel a shorter distance and less is dissolved away. For the same reason the raindrops do not fall thickly, for, since they suddenly condense into large drops at one time, they are not divided into many parts, and also fall very quickly — and that is why the stuff of rain and hail does not fall so thickly.
Deinde cum dicit: minus autem aestate etc., assignat rationem de tempore generationis grandinis. Et dicit quod minus cadunt grandines in aestate quam in vere et in autumno, sed magis quam in hieme. Ideo autem minus in aestate quam in vere et autumno, quia in aestate est siccior aer; in vere autem est adhuc humidus, propter hiemem praecedentem, et in autumno iam incipit humectari. Et sic in aestate non est tanta materia vaporum humidorum ad generationem grandinis, sicut in vere et in autumno, licet sit maior calor. In hieme autem, licet abundet materia, deficit tamen calor qui sit potens concludere frigidum ad generationem grandinis. Fiunt etiam grandines tempore maturationis fructuum, idest in fine aestatis, propter eandem causam: quia tunc calor adhuc viget, et etiam aer iam incipit humectari. 121. Then [117] he assigns a reason for the time when hail is generated, and says that hail falls less in summer than in spring and autumn, but more than in winter: less in summer than in spring and autumn, because in summer the air is drier; but in spring the air is still moist on account of the preceding winter, while in autumn, it is already beginning to grow moist. Hence in summer there is not as much moist vapor for generation of hail as in spring and autumn, although there is more heat. But in winter, although there is an abundance of material, there is lack of heat to concentrate the cold that generates hail. Also hail occurs at harvest time, i.e., in late summer, for the same reason: because the heat is then still potent and the air is beginning to get moist.
Deinde cum dicit: confert autem etc., quia difficultatem superius motam solverat propter velocitatem generationis grandinis, contingentem ex vehementia frigoris, ponit hic quoddam aliud conferens ad celeritatem eandem. Et dicit quod confert ad celeritatem coagulationis, quod aqua fuit praecalefacta, adiuvante materia vaporosa caliditatem temporis: et ideo citius infrigidatur, quia frigus vehementius agit in ipsam, et potest intrinsecus penetrare aquam rarefactam per calorem. Et ideo multi, cum volunt infrigidare calidam aquam, ponunt eam ad solem primo. Et illi etiam qui piscantur in regione Ponti, cum fecerint habitacula tempore glaciei ad venandum pisces, quos venantur scindentes glaciem fluviorum vel maris, circumfundunt aquam calidam calamis quibus venantur, ut citius coaguletur; et sic utuntur glacie quasi plumbo, ut calami firmiter quiescant. Sed et in regionibus et in temporibus calidis aqua calida fit cito frigida, eo quod cito inspissatur, propter praedictam causam. Et ideo in Arabia et Aethiopia fiunt pluviae aestate et non hieme: quia scilicet vapores cito infrigidantur ex contrarietate calidi circumstantis, cum regio illa sit valde calida. 122. Then [118], because he had solved the difficulty raised above by citing the speed with which hail is generated on account of the vigorous cold, he now posits something else that contributes to this same speed. And he says that a contribution to the speed of the coagulating process is the fact that the water is pre-heated (the vaporous stuff aiding the season's heat) and therefore freezes more quickly, because the cold acts upon it more vigorously and can penetrate farther into water that has been rarified by the heat. This is the reason why many people; when they want to cool warm water, first place it in the sun. And fishermen in the region of Pontus, when they make huts during the ice season to fish (they catch the fish through holes cut in the ice of the sea or river), pour hot water around the poles they use for fishing, so that it will freeze faster; in this way they use the frozen water, as though it were lead, to keep the poles firmly fixed. But in warm regions and in warm seasons, hot water cools quickly, because it gets dense quickly, for the reason given. Hence,-in Arabia and Ethiopia, rains occur in summer and not in winter, because the vapors are quickly cooled by reason of the contrariety of the heat surrounding them, since this region is very hot.
Ultimo autem epilogat quae dicta sunt: et est planum in littera. Finally [119] he summarizes what has been said — and this is plain in the text.

Lecture 16
The cause of the generation of rivers
Chapter 13
περὶ δὲ ἀνέμων καὶ πάντων πνευμάτων, ἔτι δὲ ποταμῶν καὶ θαλάττης λέγωμεν, πρῶτον καὶ περὶ ούτων διαπορήσαντες πρὸς ἡμᾶς αὐτούς ὥσπερ γὰρ καὶ περὶ ἄλλων, οὕτως καὶ περὶ τούτων οὐδὲν παρειλήφαμεν λεγόμενον τοιοῦτον ὃ μὴ κἂν ὁ τυχὼν εἴπειεν. 120 Let us explain the nature of winds, and all windy vapours, also of rivers and of the sea. But here, too, we must first discuss the difficulties involved: for, as in other matters, so in this no theory has been handed down to us that the most ordinary man could not have thought of.
εἰσὶ δέ τινες οἵ φασι τὸν καλούμενον ἀέρα κινούμενον μὲν καὶ ῥέοντα ἄνεμον εἶναι, συνιστάμενον δὲ τὸν αὐτὸν τοῦτον πάλιν νέφος καὶ ὕδωρ, ὡς τῆς αὐτῆς φύσεως οὔσης ὕδατος καὶ πνεύματος, καὶ τὸν ἄνεμον εἶναι κίνησιν ἀέρος. διὸ καὶ τῶν σοφῶς βουλομένων λέγειν τινὲς ἕνα φασὶν ἄνεμον εἶναι πάντας τοὺς ἀνέμους, ὅτι συμπέπτωκε καὶ τὸν ἀέρα τὸν κινούμενον ἕνα καὶ τὸν αὐτὸν εἶναι πάντα, δοκεῖν δὲ διαφέρειν οὐδὲν διαφέροντα διὰ τοὺς τόπους ὅθεν ἂν τυγχάνῃ ῥέων ἑκάστοτε, παραπλησίως λέγοντες ὥσπερ ἂν εἴ τις οἴοιτο καὶ τοὺς ποταμοὺς πάντας ἕνα ποταμὸν εἶναι. διὸ βέλτιον οἱ πολλοὶ λέγουσιν ἄνευ ζητήσεως τῶν μετὰ ζητήσεως οὕτω λεγόντων εἰ μὲν γὰρ ἐκ μιᾶς ἀρχῆς ἅπαντες ῥέουσι, κἀκεῖ τὰ πνεύματα τὸν αὐτὸν τρόπον, τάχα λέγοιεν ἄν τι οἱ λέγοντες οὕτως εἰ δ' ὁμοίως ἐνταῦθα κἀκεῖ, δῆλον ὅτι τὸ κόμψευμα ἂν εἴη τοῦτο ψεῦδος, ἐπεὶ τοῦτό γε προσήκουσαν ἔχει σκέψιν, τί τ' ἐστὶν ὁ ἄνεμος, καὶ γίγνεται πῶς, καὶ τί τὸ κινοῦν, καὶ ἡ ἀρχὴ πόθεν αὐτῶν, καὶ πότερον ἄρ' ὥσπερ ἐξ ἀγγείου δεῖ λαβεῖν ῥέοντα τὸν ἄνεμον, καὶ μέχρι τούτου ῥεῖν ἕως ἂν κενωθῇ τὸ ἀγγεῖον, οἷον ἐξ ἀσκῶν ἀφιέμενον, (349b.) ἢ καθάπερ καὶ οἱ γραφεῖς γράφουσιν, ἐξ αὑτῶν τὴν ἀρχὴν ἀφιέντας. 121 Some say that what is called air, when it is in motion and flows, is wind, and that this same air when it condenses again becomes cloud and water, implying that the nature of wind and water is the same. So they define wind as a motion of the air. Hence some, wishing to say a clever thing, assert that all the winds are one wind, because the air that moves is in fact all of it one and the same; they maintain that the winds appear to differ owing to the region from which the air may happen to flow on each occasion, but really do not differ at all. This is just like thinking that all rivers are one and the same river, and the ordinary unscientific view is better than a scientific theory like this. If all rivers flow from one source, and the same is true in the case of the winds, there might be some truth in this theory; but if it is no more true in the one case than in the other, this ingenious idea is plainly false. What requires investigation is this: the nature of wind and how it originates, its efficient cause and whence they derive their source; whether one ought to think of the wind as issuing from a sort of vessel and flowing until the vessel is empty, as if let out of a wineskin, or, as painters represent the winds, as drawing their source from themselves.
ὁμοίως δὲ καὶ περὶ τῆς τῶν ποταμῶν γενέσεως δοκεῖ τισιν ἔχειν τὸ γὰρ ἀναχθὲν ὑπὸ τοῦ ἡλίου ὕδωρ πάλιν ὑόμενον ἀθροισθὲν ὑπὸ γῆν ῥεῖν ἐκ κοιλίας μεγάλης, ἢ πάντας μιᾶς ἢ ἄλλον ἄλλης καὶ οὐ γίγνεσθαι ὕδωρ οὐδέν, ἀλλὰ τὸ συλλεχθὲν ἐκ τοῦ χειμῶνος εἰς τὰς τοιαύτας ὑποδοχάς, τοῦτο γίγνεσθαι τὸ πλῆθος τὸ τῶν ποταμῶν. διὸ καὶ μείζους ἀεὶ τοῦ χειμῶνος ῥεῖν ἢ τοῦ θέρους, καὶ τοὺς μὲν ἀενάους εἶναι τοὺς δ' οὐκ ἀενάους ὅσων μὲν γὰρ διὰ τὸ μέγεθος τῆς κοιλίας πολὺ τὸ συλλεγόμενον ὕδωρ ἐστίν, ὥστε διαρκεῖν καὶ μὴ προαναλίσκεσθαι πρὶν ἐπελθεῖν τὸ ὄμβριον ἐν τῷ χειμῶνι πάλιν, τούτους μὲν ἀενάους εἶναι διὰ τέλους, ὅσοις δὲ ἐλάττους αἱ ὑποδοχαί, τούτους δὲ δι' ὀλιγότητα τοῦ ὕδατος φθάνειν ξηραινομένους πρὶν ἐπελθεῖν τὸ ἐκ τοῦ οὐρανοῦ, κενουμένου τοῦ ἀγγείου. 122 We find analogous views about the origin of rivers. It is thought that the water is raised by the sun and descends in rain and gathers below the earth and so flows from a great reservoir, all the rivers from one, or each from a different one. No water at all is generated, but the volume of the rivers consists of the water that is gathered into such reservoirs in winter. Hence rivers are always fuller in winter than in summer, and some are perennial, others not. Rivers are perennial where the reservoir is large and so enough water has collected in it to last out and not be used up before the winter rain returns. Where the reservoirs are smaller there is less water in the rivers, and they are dried up and their vessel empty before the fresh rain comes on.
καίτοι φανερόν, εἴ τις βούλεται ποιήσας οἷον ὑποδοχὴν πρὸ ὀμμάτων τῷ καθ' ἡμέραν ὕδατι ῥέοντι συνεχῶς νοῆσαι τὸ πλῆθος ὑπερβάλλοι γὰρ ἂν τῷ μεγέθει τὸν τῆς γῆς ὄγκον ἢ οὐ πολὺ ἂν ἐλλείποι τὸ δεχόμενον πᾶν τὸ ῥέον ὕδωρ εἰς τὸν ἐνιαυτόν. ἀλλὰ δῆλον ὅτι συμβαίνει μὲν καὶ πολλὰ τοιαῦτα πολλαχοῦ τῆς γῆς, 123 But if any one will picture to himself a reservoir adequate to the water that is continuously flowing day by day, and consider the amount of the water, it is obvious that a receptacle that is to contain all the water that flows in the year would be larger than the earth, or, at any rate, not much smaller. Though it is evident that many reservoirs of this kind do exist in many parts of the earth,
οὐ μὴν ἀλλ' ἄτοπον εἴ τις μὴ νομίζει διὰ τὴν αὐτὴν αἰτίαν ὕδωρ ἐξ ἀέρος γίγνεσθαι δι' ἥνπερ ὑπὲρ γῆς καὶ ἐν τῇ γῇ. ὥστ' εἴπερ κἀκεῖ διὰ ψυχρότητα συνίσταται ὁ ἀτμίζων ἀὴρ εἰς ὕδωρ, καὶ ὑπὸ τῆς ἐν τῇ γῇ ψυχρότητος τὸ αὐτὸ τοῦτο δεῖ νομίζειν συμβαίνειν, καὶ γίγνεσθαι μὴ μόνον τὸ ἀποκεκριμένον ὕδωρ ἐν αὐτῇ, καὶ τοῦτο ῥεῖν, ἀλλὰ καὶ γίγνεσθαι συνεχῶς. 123 yet it is unreasonable for any one to refuse to admit that air becomes water in the earth for the same reason as it does above it. If the cold causes the vaporous air to condense into water above the earth we must suppose the cold in the earth to produce this same effect, and recognize that there not only exists in it and flows out of it actually formed water, but that water is continually forming in it too.
ἔτι δὲ τοῦ μὴ γιγνομένου ἀλλ' ὑπάρχοντος ὕδατος καθ' ἡμέραν μὴ τοιαύτην εἶναι τὴν ἀρχὴν τῶν ποταμῶν, οἷον ὑπὸ γῆν λίμνας τινὰς ἀποκεκριμένας, καθάπερ ἔνιοι λέγουσιν, ἀλλ' ὁμοίως ὥσπερ καὶ ἐν τῷ ὑπὲρ γῆς τόπῳ μικραὶ συνιστάμεναι ῥανίδες, καὶ πάλιν αὗται ἑτέραις, τέλος μετὰ πλήθους καταβαίνει τὸ ὑόμενον ὕδωρ, οὕτω καὶ ἐν τῇ γῇ ἐκ μικρῶν συλλείβεσθαι τὸ πρῶτον καὶ εἶναι οἷον πιδώσης εἰς ἓν τῆς γῆς τὰς ἀρχὰς τῶν ποταμῶν. δηλοῖ δ' αὐτὸ τὸ ἔργον οἱ γὰρ τὰς ὑδραγωγίας (350a.) ποιοῦντες ὑπονόμοις καὶ διώρυξι συνάγουσιν, ὥσπερ ἂν ἰδιούσης τῆς γῆς ἀπὸ τῶν ὑψηλῶν. 125 Again, even in the case of the water that is not being formed from day to day but exists as such, we must not suppose as some do that rivers have their source in definite subterranean lakes. On the contrary, just as above the earth small drops form and these join others, till finally the water descends in a body as rain, so too we must suppose that in the earth the water at first trickles together little by little, and that the sources of the rivers drip, as it were, out of the earth and then unite. This is proved by facts. When men construct an aqueduct they collect the water in pipes and trenches, as if the earth in the higher ground were sweating the water out.
διὸ καὶ τὰ ῥεύματα τῶν ποταμῶν ἐκ τῶν ὀρῶν φαίνεται ῥέοντα, καὶ πλεῖστοι καὶ μέγιστοι ποταμοὶ ῥέουσιν ἐκ τῶν μεγίστων ὀρῶν. ὁμοίως δὲ καὶ αἱ κρῆναι αἱ πλεῖσται ὄρεσιν καὶ τόποις ὑψηλοῖς γειτνιῶσιν ἐν δὲ τοῖς πεδίοις ἄνευ ποταμῶν ὀλίγαι γίγνονται πάμπαν. οἱ γὰρ ὀρεινοὶ καὶ ὑψηλοὶ τόποι, οἷον σπόγγος πυκνὸς ἐπικρεμάμενοι, κατὰ μικρὰ μὲν πολλαχῇ δὲ διαπιδῶσι καὶ συλλείβουσι τὸ ὕδωρ δέχονταί τε γὰρ τοῦ κατιόντος ὕδατος πολὺ πλῆθος (τί γὰρ διαφέρει κοίλην καὶ ὑπτίαν ἢ πρηνῆ τὴν περιφέρειαν εἶναι καὶ κυρτήν; ἀμφοτέρως γὰρ τὸν ἴσον ὄγκον περιλήψεται σώματος) καὶ τὴν ἀνιοῦσαν ἀτμίδα ψύχουσι καὶ συγκρίνουσι πάλιν εἰς ὕδωρ διό, καθάπερ εἴπομεν, οἱ μέγιστοι τῶν ποταμῶν ἐκ τῶν μεγίστων φαίνονται ῥέοντες ὀρῶν. δῆλον δ' ἐστὶ τοῦτο θεωμένοις τὰς τῆς γῆς περιόδους ταύτας γὰρ ἐκ τοῦ πυνθάνεσθαι παρ' ἑκάστων οὕτως ἀνέγραψαν, ὅσων μὴ συμβέβηκεν αὐτόπτας γενέσθαι τοὺς λέγοντας. ἐν μὲν οὖν τῇ Ἀσίᾳ πλεῖστοι μὲν ἐκ τοῦ Παρνασσοῦ καλουμένου φαίνονται ῥέοντες ὄρους καὶ μέγιστοι ποταμοί, τοῦτο δ' ὁμολογεῖται πάντων εἶναι μέγιστον τὸ ὄρος τῶν πρὸς τὴν ἕω τὴν χειμερινήν ὑπερβάντι γὰρ ἤδη τοῦτο φαίνεται ἡ ἔξω θάλαττα, ἧς τὸ πέρας οὐ δῆλον τοῖς ἐντεῦθεν. ἐκ μὲν οὖν τούτου ῥέουσιν ἄλλοι τε ποταμοὶ καὶ ὁ Βάκτρος καὶ ὁ Χοάσπης καὶ ὁ Ἀράξης τούτου δ' ὁ Τάναϊς ἀποσχίζεται μέρος ὢν εἰς τὴν Μαιῶτιν λίμνην. ῥεῖ δὲ καὶ ὁ Ἰνδὸς ἐξ αὐτοῦ, πάντων τῶν ποταμῶν ῥεῦμα πλεῖστον. ἐκ δὲ τοῦ Καυκάσου ἄλλοι τε ῥέουσι πολλοὶ καὶ κατὰ πλῆθος καὶ κατὰ μέγεθος ὑπερβάλλοντες, καὶ ὁ Φᾶσις ὁ δὲ Καύκασος μέγιστον ὄρος τῶν πρὸς τὴν ἕω τὴν θερινήν ἐστιν καὶ πλήθει καὶ ὕψει. σημεῖα δὲ τοῦ μὲν ὕψους ὅτι ὁρᾶται καὶ ἀπὸ τῶν καλουμένων βαθέων καὶ εἰς τὴν λίμνην εἰσπλεόντων, ἔτι δ' ἡλιοῦται τῆς νυκτὸς αὐτοῦ τὰ ἄκρα μέχρι τοῦ τρίτου μέρους ἀπό τε τῆς ἕω καὶ πάλιν ἀπὸ τῆς ἑσπέρας τοῦ δὲ πλήθους ὅτι πολλὰς ἔχον ἕδρας, ἐν αἷς ἔθνη τε κατοικεῖ πολλὰ καὶ λίμνας εἶναί φασι μεγάλας, ἀλλ' ὅμως πάσας τὰς ἕδρας εἶναί φασι φανερὰς μέχρι τῆς ἐσχάτης κορυφῆς. ἐκ δὲ (350b.) τῆς Πυρήνης (τοῦτο δ' ἐστὶν ὄρος πρὸς δυσμὴν ἰσημερινὴν ἐν τῇ Κελτικῇ) ῥέουσιν ὅ τε Ἴστρος καὶ ὁ Ταρτησσός. οὗτος μὲν οὖν ἔξω στηλῶν, ὁ δ' Ἴστρος δι' ὅλης τῆς Εὐρώπης εἰς τὸν Εὔξεινον πόντον. τῶν δ' ἄλλων ποταμῶν οἱ πλεῖστοι πρὸς ἄρκτον ἐκ τῶν ὀρῶν τῶν Ἀρκυνίων ταῦτα δὲ καὶ ὕψει καὶ πλήθει μέγιστα περὶ τὸν τόπον τοῦτόν ἐστιν. ὑπ' αὐτὴν δὲ τὴν ἄρκτον ὑπὲρ τῆς ἐσχάτης Σκυθίας αἱ καλούμεναι Ῥῖπαι, περὶ ὧν τοῦ μεγέθους λίαν εἰσὶν οἱ λεγόμενοι λόγοι μυθώδεις ῥέουσι δ' οὖν οἱ πλεῖστοι καὶ μέγιστοι μετὰ τὸν Ἴστρον τῶν ἄλλων ποταμῶν ἐντεῦθεν, ὥς φασιν. ὁμοίως δὲ καὶ περὶ τὴν Λιβύην οἱ μὲν ἐκ τῶν Αἰθιοπικῶν ὀρῶν, ὅ τε Αἰγὼν καὶ ὁ Νύσης, οἱ δὲ μέγιστοι τῶν διωνομασμένων, ὅ τε Χρεμέτης καλούμενος, ὃς εἰς τὴν ἔξω ῥεῖ θάλατταν, καὶ τοῦ Νείλου τὸ ῥεῦμα τὸ πρῶτον, ἐκ τοῦ Ἀργυροῦ καλουμένου ὄρους. τῶν δὲ περὶ τὸν Ἑλληνικὸν τόπον ὁ μὲν Ἀχελῷος ἐκ Πίνδου, καὶ ὁ Ἴναχος ἐντεῦθεν, ὁ δὲ Στρυμὼν καὶ Νέσσος καὶ ὁ Ἕβρος ἅπαντες τρεῖς ὄντες ἐκ τοῦ Σκόμβρου πολλὰ δὲ ῥεύματα καὶ ἐκ τῆς Ῥοδόπης ἐστίν. ὁμοίως δὲ καὶ τοὺς ἄλλους ποταμοὺς εὕροι τις ἂν ῥέοντας ἀλλὰ μαρτυρίου χάριν τούτους εἴπομεν ἐπεὶ καὶ ὅσοι αὐτῶν ῥέουσιν ἐξ ἑλῶν, τὰ ἕλη ὑπὸ ὄρη κεῖσθαι συμβαίνει πάντα σχεδὸν ἢ τόπους ὑψηλοὺς ἐκ προσαγωγῆς. 126 Hence, too, the head-waters of rivers are found to flow from mountains, and from the greatest mountains there flow the most numerous and greatest rivers. Again, most springs are in the neighbourhood of mountains and of high ground, whereas if we except rivers, water rarely appears in the plains. For mountains and high ground, suspended over the country like a saturated sponge, make the water ooze out and trickle together in minute quantities but in many places. They receive a great deal of water falling as rain (for it makes no difference whether a spongy receptacle is concave and turned up or convex and turned down: in either case it will contain the same volume of matter) and, they also cool the vapour that rises and condense it back into water. Hence, as we said, we find that the greatest rivers flow from the greatest mountains. This can be seen by looking at itineraries: what is recorded in them consists either of things which the writer has seen himself or of such as he has compiled after inquiry from those who have seen them. In Asia we find that the most numerous and greatest rivers flow from the mountain called Parnassus, admittedly the greatest of all mountains towards the south-east. When you have crossed it you see the outer ocean, the further limit of which is unknown to the dwellers in our world. Besides other rivers there flow from it the Bactrus, the Choaspes, the Araxes: from the last a branch separates off and flows into lake Maeotis as the Tanais. From it, too, flows the Indus, the volume of whose stream is greatest of all rivers. From the Caucasus flows the Phasis, and very many other great rivers besides. Now the Caucasus is the greatest of the mountains that lie to the northeast, both as regards its extent and its height. A proof of its height is the fact that it can be seen from the so-called 'deeps' and from the entrance to the lake. Again, the sun shines on its peaks for a third part of the night before sunrise and again after sunset. Its extent is proved by the fact that thought contains many inhabitable regions which are occupied by many nations and in which there are said to be great lakes, yet they say that all these regions are visible up to the last peak. From Pyrene (this is a mountain towards the west in Celtice) there flow the Istrus and the Tartessus. The latter flows outside the pillars, while the Istrus flows through all Europe into the Euxine. Most of the remaining rivers flow northwards from the Hercynian mountains, which are the greatest in height and extent about that region. In the extreme north, beyond furthest Scythia, are the mountains called Rhipae. The stories about their size are altogether too fabulous: however, they say that the most and (after the Istrus) the greatest rivers flow from them. So, too, in Libya there flow from the Aethiopian mountains the Aegon and the Nyses; and from the so-called Silver Mountain the two greatest of named rivers, the river called Chremetes that flows into the outer ocean, and the main source of the Nile. Of the rivers in the Greek world, the Achelous flows from Pindus, the Inachus from the same mountain; the Strymon, the Nestus, and the Hebrus all three from Scombrus; many rivers, too, flow from Rhodope. All other rivers would be found to flow in the same way, but we have mentioned these as examples. Even where rivers flow from marshes, the marshes in almost every case are found to lie below mountains or gradually rising ground.
ὅτι μὲν οὖν οὐ δεῖ νομίζειν οὕτω γίγνεσθαι τὰς ἀρχὰς τῶν ποταμῶν ὡς ἐξ ἀφωρισμένων κοιλιῶν, φανερόν οὔτε γὰρ ἂν ὁ τόπος ἱκανὸς ἦν ὁ τῆς γῆς ὡς εἰπεῖν, ὥσπερ οὐδ' ὁ τῶν νεφῶν, εἰ τὸ ὂν ἔδει ῥεῖν μόνον, ἀλλὰ μὴ τὸ μὲν ἀπῄει τὸ δ' ἐγίγνετο, ἀλλ' αἰεὶ ἀπὸ ὄντος ἐταμιεύετο τό τε ὑπὸ τοῖς ὄρεσιν ἔχειν τὰς πηγὰς μαρτυρεῖ διότι τῷ συρρεῖν εἰς ὀλίγον καὶ κατὰ μικρὸν ἐκ πολλῶν νοτίδων διαδίδωσιν ὁ τόπος καὶ γίγνονται οὕτως αἱ πηγαὶ τῶν ποταμῶν. 127 It is clear then that we must not suppose rivers to originate from definite reservoirs: for the whole earth, we might almost say, would not be sufficient (any more than the region of the clouds would be) if we were to suppose that they were fed by actually existing water only and it were not the case that as some water passed out of existence some more came into existence, but rivers always drew their stream from an existing store. Secondly, the fact that rivers rise at the foot of mountains proves that a place transmits the water it contains by gradual percolation of many drops, little by little, and that this is how the sources of rivers originate.
οὐ μὴν ἀλλὰ καὶ τοιούτους εἶναι τόπους ἔχοντας πλῆθος ὕδατος, οἷον λίμνας, οὐδὲν ἄτοπον, πλὴν οὔτι τηλικαύτας ὥστε τοῦτο συμβαίνειν, οὐδὲν μᾶλλον ἢ εἴ τις οἴοιτο τὰς φανερὰς εἶναι πηγὰς τῶν ποταμῶν σχεδὸν γὰρ ἐκ κρηνῶν οἱ πλεῖστοι ῥέουσιν. ὅμοιον οὖν τὸ ἐκείνας καὶ τὸ ταύτας νομίζειν εἶναι τὸ σῶμα τὸ τοῦ ὕδατος πᾶν. ὅτι δ' εἰσὶν τοιαῦται φάραγγες καὶ διαστάσεις τῆς γῆς, (351a.) δηλοῦσιν οἱ καταπινόμενοι τῶν ποταμῶν. συμβαίνει δὲ τοῦτο πολλαχοῦ τῆς γῆς, οἷον τῆς μὲν Πελοποννήσου πλεῖστα τοιαῦτα περὶ τὴν Ἀρκαδίαν ἐστίν. αἴτιον δὲ διὰ τὸ ὀρεινὴν οὖσαν μὴ ἔχειν ἐκροὰς ἐκ τῶν κοίλων εἰς θάλατταν πληρούμενοι γὰρ οἱ τόποι καὶ οὐκ ἔχοντες ἔκρυσιν αὑτοῖς εὑρίσκονται τὴν δίοδον εἰς βάθος, ἀποβιαζομένου τοῦ ἄνωθεν ἐπιόντος ὕδατος. περὶ μὲν οὖν τὴν Ἑλλάδα μικρὰ τοιαῦτα παντελῶς ἐστιν γιγνόμενα ἀλλ' ἥ γε ὑπὸ τὸν Καύκασον λίμνη, ἣν καλοῦσιν οἱ ἐκεῖ θάλατταν αὕτη γὰρ ποταμῶν πολλῶν καὶ μεγάλων εἰσβαλλόντων οὐκ ἔχουσα ἔκρουν φανερὸν ἐκδίδωσιν ὑπὸ γῆν κατὰ Κοραξούς, περὶ τὰ καλούμενα βαθέα τοῦ Πόντου ταῦτα δ' ἐστὶν ἄπειρόν τι τῆς θαλάττης βάθος οὐδεὶς γοῦν πώποτε καθεὶς ἐδυνήθη πέρας εὑρεῖν. ταύτῃ δὲ πόρρω τῆς γῆς σχεδὸν περὶ τριακόσια στάδια πότιμον ἀναδίδωσιν ὕδωρ ἐπὶ πολὺν τόπον, οὐ συνεχῆ δέ, ἀλλὰ τρισσαχῇ. καὶ περὶ τὴν Λιγυστικὴν οὐκ ἐλάττων τοῦ Ῥοδανοῦ καταπίνεταί τις ποταμός, καὶ πάλιν ἀναδίδωσιν κατ' ἄλλον τόπον ὁ δὲ Ῥοδανὸς ποταμὸς ναυσιπέρατός ἐστιν. 128 However, there is nothing impossible about the existence of such places containing a quantity of water like lakes: only they cannot be big enough to produce the supposed effect. To think that they are is just as absurd as if one were to suppose that rivers drew all their water from the sources we see (for most rivers do flow from springs). So it is no more reasonable to suppose those lakes to contain the whole volume of water than these springs. That there exist such chasms and cavities in the earth we are taught by the rivers that are swallowed up. They are found in many parts of the earth: in the Peloponnesus, for instance, there are many such rivers in Arcadia. The reason is that Arcadia is mountainous and there are no channels from its valleys to the sea. So these places get full of water, and this, having no outlet, under the pressure of the water that is added above, finds a way out for itself underground. In Greece this kind of thing happens on quite a small scale, but the lake at the foot of the Caucasus, which the inhabitants of these parts call a sea, is considerable. Many great rivers fall into it and it has no visible outlet but issues below the earth off the land of the Coraxi about the so-called 'deeps of Pontus'. This is a place of unfathomable depth in the sea: at any rate no one has yet been able to find bottom there by sounding. At this spot, about three hundred stadia from land, there comes up sweet water over a large area, not all of it together but in three places. And in Liguria a river equal in size to the Rhodanus is swallowed up and appears again elsewhere: the Rhodanus being a navigable river.
Postquam philosophus determinavit de his quae generantur in alto ab exhalatione humida, hic determinat de his quae generantur in terra ex eadem materia, scilicet de fontibus et fluminibus. Et dividitur in partes duas: 123. After determining concerning things generated on high from the moist exhalation, the Philosopher here determines about things generated on earth from the same material — namely, about springs and rivers. It is divided into two parts:

in prima determinat de causa generationis fluviorum;

in secunda de duratione eorum, ibi: non semper autem eadem loca et cetera.

In the first he determines concerning the cause of the generation of rivers;

In the second concerning their duration (L. 17).

Circa primum tria facit. Primo dicit de quo est intentio. Et dicit quod est de ventis et omnibus quae ex ventis causantur, et de fluviis et de mari. De quibus hoc ordine dicetur, quod primo proponemus dubitationes ad nosipsos, et postea declarabimus veritatem ad nosipsos, et non ad alios: quia de talibus nihil accepimus dictum ab aliis, quod non quilibet possit dicere, sicut et circa alias materias contingit. As to the first, he does three things: first, he states his intention [120] and says that the discussion is about winds and everything caused by winds, and about rivers and the sea. These will be treated in the following order: we shall propose problems of our own; then we shall declare the true answer to the problems to ourselves and not others: since on these matters we have received no opinions from others that anybody could not have conceived, unlike that which was the case in regard to the other matters.
Secundo ibi: sunt autem quidam etc., ponit opiniones quorundam de ventis. Et dicit quod quidam dixerunt quod corpus quod dicitur aer, dum fluit et movetur, est ventus; dum autem constat et inspissatur, est nubes et aqua; ac si eadem natura sit aquae, aeris et venti, et nihil aliud sit ventus quam aer et aqua. Et quia aer totus est unus, ideo quidam, volentes multum sapienter loqui, dixerunt quod non est nisi unus ventus; et quod videantur venti differre, hoc non est nisi ex differentia locorum ex quibus moventur. Quod est simile ac si dicerent quod omnes fluvii sunt unus fluvius, et quod omnis aqua est una: quod manifeste falsum est. Unde multitudo hominum, qui vulgariter et sine inquisitione philosophiae loquuntur de ventis, melius loquuntur quam isti, qui sic inquirendo erraverunt. Quia si hoc esset verum, quod omnes fluvii fluerent ex uno principio, et hoc etiam posset aliquo modo esse verum, quod omnes venti essent ex uno principio: sed de ventis etiam, sicut de fluviis, manifestum est quod id quod dixerunt, leviter et mendaciter dixerunt. 124. Secondly [121], he presents the opinions of certain others about winds. And he says that some have declared that the body called "air," when it flows along and is in motion, is wind; but when it halts and condenses, it is cloud and water — as though the natures of water, air and wind were identical, and wind were nothing more than air and water. And because the whole of air is one, some, wishing to speak very wisely, have asserted that there is but one wind, and that if winds seem to differ, it is only because of the different places whence they move. This is like saying that all rivers are one river, and that all water is one: which is plainly false. Hence the generality of mankind, who speak as do the uneducated and without philosophic enquiry about the winds, speak with more truth than these, who in such an inquiry erred. For if it were true that all rivers flowed from one source, then it could also be somehow true that all winds were from one source: but it is plain that, for winds as well as for rivers, what they said is frivolously and deceitfully said.
Opportunum est autem de hoc considerare in proprio tractatu, quid est ventus, et quomodo generatur, et quid movet ipsum, et unde est principium ventorum; et utrum oporteat accipere ventum fluentem sicut ex aliquo vase, qui tandiu fluat donec illud evacuetur, ac si esset emissum ab aliquo utre, ut fabulatur Homerus; aut non est ex uno principio sed ex multis, sicut pictores pingunt diversos ventos emittentes ex seipsis principium flatuum. It is appropriate to discuss in a tract proper to it what wind is, and how it is generated, and what moves it, and from what do winds derive their source, and whether we must consider the wind as though flowing from some receptacle, and continuing to flow until it is emptied, as though wind were squeezed out of a wineskin as Homer's fable pretended; or whether it comes, not from one, but from many sources, as the painters depict the various winds puffing from out of themselves the source of breezes.
Tertio ibi: similiter autem de generatione etc., inducit similes opiniones de generatione fluviorum: propter hoc enim induxerat quod dictum est de ventis. Et circa hoc tria facit: 125. Thirdly [122], he presents like opinions about the generation of rivers: this was the reason he introduced what he said concerning winds. About this he does three things:

primo ponit quorundam falsam opinionem;

secundo reprobat eam, ibi: quamvis manifestum etc.;

tertio excludit quandam rationem ipsorum, ibi: non solum sed et talia et cetera.

First, he presents the false opinion of certain ones, at 125;

Secondly, he rejects it, at 126,

Thirdly, he rejects a certain argument of their, at 130.

Dicit ergo primo quod similiter videtur quibusdam se habere de generatione fluviorum, sicut dictum est de generatione ventorum. Dicunt enim quod, cum aqua elevatur a terra per vaporationem, et iterum fluit deorsum, congregatur sub terra, et sic fluit ad generationem fontium et fluviorum; sicut si intelligantur exire ex aliquo magno ventre, idest ex aliqua magna voragine, ubi sit congregata multa aqua; sive ita sit quod omnes fluvii fluant ex uno principio tali, sive ex diversis talibus principiis diversi fluvii fluant. Et secundum hoc, aqua non generatur sub terra de novo ad fluxum fontium et fluviorum; sed illa quae prius fuit collecta in praedicta receptacula, est principium multitudinis aquarum et fluviorum. He says therefore first [122], that to some, the same things seem to be true of the generation of rivers as was said of the generation of winds. For they say that when water is raised aloft through evaporation and then re-descends, it collects under the earth and thus flows on to generate springs and rivers. It is as if they were understood to emerge from some "great womb," i.e., from some large depth where a great amount of water is gathered. It makes no difference to their theory whether all rivers flow from one such source or various rivers from various sources of this sort. According to this theory water is not newly generated under the earth to cause the flow of springs and rivers: what happens is that the water previously collected in the aforesaid receptacles is the source of the amount of waters and rivers.
Et huius signum dicebant esse, quod in hieme est maior fluxus fluviorum quam in aestate. Et hinc assignant causam quare quidam fluviorum sunt perpetui, et quidam non perpetui. Quando enim, propter magnitudinem voraginis, tanta aqua congregatur in hieme sub terra, ut sufficiat ad perpetuitatem fluvii, ita quod non deficiat aqua fluens priusquam iterum superveniat in nova hieme, tunc fluvius fit perpetuus usque in finem: si autem receptaculum sit parvum, tunc propter paucitatem aquae deficit origo fluvii, quasi evacuato vase, antequam iterum fluat aqua de caelo; et ideo fluvius non perenniter fluit. And they said that a sign of this is the fact that in winter there is more river-flow than in summer. From this they assign the cause why some rivers are unceasing and some not. For when, because of the size of the depth, a sufficient amount of water gathers under the earth to assure continuity of flow, in such a way that the flowing water does not run out before returning again the next winter, then the river is made perpetual to the end. But if the reservoir is small, then, because of the smallness of the amount of water, the river's source runs dry (as an emptied vessel) before water again flows from the sky. That is why such a river does not flow perennially.
Deinde cum dicit: quamvis manifestum etc., improbat praedictam positionem quadrupliciter: primo quidem dicens quod, si aliquis velit prae oculis considerare multitudinem aquae quae continue fluit per fluvios per totum universum, excederet totam quantitatem terrae, vel parum ab ea deficeret, si oporteret esse aliquod receptaculum sub terra, vel unum vel plura, unde flumina fluerent. Et sic oporteret totam terram interius esse concavam, ad capiendam tantam multitudinem aquae; et hoc ipsum non sufficeret. 126. Then [123] he rejects this position for four reasons: First, he says that if one were to take into consideration the vast amount of water that continually flows through rivers in the entire world, the subterranean reservoir, or reservoirs, feeding these rivers, would have to be larger, or at least almost as large, as the earth. This would require that the whole interior of the earth be hollow, in order to hold such a vast amount of water; and even that would not be a sufficiently large container.
Hoc autem patet esse falsum. Cum enim terra naturaliter sit in medio, et naturaliter partes tendant ad medium, non potest dici quod terra sit tantum concava interius ad suscipiendam aquam; licet non sit inconveniens quod in multis locis terrae sint aliqua receptacula aquarum. Now this is plainly false: for, since earth is by nature in the middle [center], and its parts naturally tend to the middle, it cannot be said that the earth is hollow enough within to hold the water — although it is not inadmissible that there be certain receptacles of water in many parts of the earth.
Secundo ibi: non solum sed et inconveniens etc., ponit secundam rationem. Et dicit quod inconveniens est, si quis non putet quod ex aere evaporato intra terram fiat aqua, propter eandem causam propter quam fit etiam supra terram in aere. Unde si supra terram in aere aer evaporatus propter frigiditatem condensatur in aquam, oportet putare quod etiam a frigiditate terrae hoc idem fiat. Et sic non solum aqua separatim existens in terra quasi in aliquo receptaculo, fluet per fluvios; sed continue infra terram generatur per infrigidationem vaporum, et haec effluet per fluvios. 127. Secondly [124], he gives a second argument and says that it is inconsistent for one not to suppose that water comes to be within the earth from evaporated air, for the same reason that it is produced above the earth in the air. Hence, if evaporated air is condensed into water in the air above the earth on account of coldness, one must believe that the same is produced by reason of the coldness of the earth. And so, not only water existing separated in the earth as in a reservoir, flows through rivers, but water is also being continually generated within the earth by the refrigeration of vapors, and this will flow out through rivers.
Sed quia posset aliquis dicere quod ex vaporibus infra terram generatur quaedam aqua, sed tota simul colligitur in aliquibus receptaculis, ex quibus fluvii fluunt, quod esset simile et quasi idem positioni praedictae, ideo tertio hoc excludit per quoddam signum, ibi: adhuc autem et cetera. Et dicit quod adhuc non est intelligendum tale esse principium fluviorum, quod aqua quidem generetur infra terram, sed existat ibi quotidie dum flumina fluunt, ac si essent quaedam stagna aquarum sub terra, ut quidam dicunt: sed oportet intelligere sic fieri intra terram, sicut fit supra terram. Supra terram enim, dum primo condensatur vapor, fiunt parvae guttae, quae adunantur cum aliis; et sic facile aqua fluens descendit cum quadam multitudine. Ita etiam fit infra terram: primo enim parvae guttae generantur; et sic principia fluviorum sunt quaedam scaturigines paulatim scaturientes in imo terrae. 128. But because someone could say that a certain water is generated within the earth from vapors, but that the whole is collected together into certain reservoirs, whence rivers flow, which theory would be similar to, and practically the same as, the previous position, therefore, thirdly, he rejects this by means of a sign at [125]. And he says that it is even not to be supposed that water indeed is generated within the earth but remains there from day to day while rivers flow, as though there were certain pools of water under the earth, as some say. But one must understand that things take place in the same way within the earth, as above the earth. For above the earth, when vapor is first being condensed, small drops form and coalesce with others and in this way the flowing water easily descends in a certain quantity. The same thing takes place within the earth: for first small drops are generated; and thus the sources of rivers are springs gushing little by little below the earth.
Et hoc manifestatur per opus: qui enim volunt ducere aquas, puta facientes puteos vel aliquid tale, colligunt aquas in locis infimis et defossis, ac si fieret quaedam resudatio terrae per aquam a locis excelsis ad infima. Et ex hoc apparet quod aqua guttatim profluit a terra ad generationem fluviorum et fontium; non autem ita quod infra terram sint loca quae sint quasi stagna aquarum actu existentium. An indication of this is what is done — for people who wish to bring out water, e.g., who dig wells or the like, collect the water in low and excavated places, as though the earth perspired water from elevated areas to lower areas. From which it appears that water flows drop by drop from the earth to produce rivers and springs, rather than that in the earth are places acting as pools of actually existing water.
Quarto ibi: propter quod et rheumata etc., ponit aliud signum ad idem, sumptum ex naturali fluxu aquarum: nam praecedens signum fuit sumptum ex opere. Et dicit quod propter eandem causam rheumata, idest fluviorum fluxus, videntur esse ex montibus, et maximi fluvii fluunt ex maximis montibus; et fontes, ut plurimum, sunt vicini montibus et locis altis; sed in campestribus sunt pauci fontes separati a fluviis. Et hoc ideo est, quia loca montana et alta sunt sicut quaedam spongia spissa, propter soliditatem lapidum, ad eiiciendam aquam; et sunt suspensa, ad hoc quod aqua possit fluere; et sic producunt aquam in multis locis; et colligunt etiam aquam desuper complutam. Sed hoc secundum modicas partes, non tamen ita quod infra montes sint voragines in quibus congregatur aqua. Et ideo dicit quod colligunt aquam, quia suscipiunt magnam multitudinem aquae desuper advenientis per pluviam. Et ad hoc cooperatur figura montium: nam figura rotunda est capacissima figurarum. 129. Fourthly [126], he supports the same view with another sign, based on the natural flow of waters: for the previous sign was based on a [human] work. And he says that for the same reason, the "discharge," i.e., the flow of rivers, seems to be from the mountains, and the largest rivers flow from the largest mountains; moreover, most springs are close to mountains and high places, whereas on the plains there are few springs apart from rivers. The reason is that mountainous and high places are like certain thick sponges (because the rocks are hard) as to ejecting water; and they are suspended [elevated], so that the water can flow: consequently, they produce water in many places and also collect water that comes down from above as rain. But this occurs in small sections of the mountains and not in the sense that within the mountains there are depths in which water is gathered. That is why he says that they collect water, for they receive a great abundance of water coming as rainfall. The shape of mountains is well-adapted for this, for a round shape is the most capacious of shapes.
Nihil autem differt ad recipiendam multitudinem aquae, an circumferentia sit disposita supreme secundum concavitatem, an secundum convexam gibbositatem: quia utroque modo aequalem quantitatem capiet. Unde licet montes non sint positi secundum concavitatem, sed magis secundum gibbositatem, tamen multitudinem aquarum recipere possunt. Et non solum colligunt multitudinem aquarum ut aliunde receptam, propter figuram, sed etiam producunt eam ut interius generatam propter frigiditatem: quia vaporem resolutum a terra, et ascendentem propter caliditatem innatam, frigiditas terrae infra terram partim coagulat, et sic iterum condensat ipsum in aquam. Et ideo, ut dictum est, maximi fluviorum fluunt ex maximis montibus. So far as holding a great amount of water is concerned, it makes no difference whether the circumference is disposed above in a concave way, or according to a convex swelling — for in either case the capacity is equal. Hence, although mountains are not concave, but more convex, nevertheless they can receive a vast amount of water. And they not only hold a great amount of water as received from elsewhere, because of their shape, but also bring it forth as water born within because of the cold: for the vapor of earth, drawn out of the earth, and rising because of its inherent warmth, is coagulated within the earth by the coldness of the earth, so that it is again condensed into water. And that is why, as was said, the largest rivers flow from the largest mountains.
Et hoc manifestum est, si quis consideret circularem descriptionem terrae: qui enim sic descripserunt terram, vel ipsi viderunt flumina et regiones, vel ab aliis inquisiverunt. Ponit ergo exemplum primo quidem in Asia de Parnaso, qui est ad ortum hiemalem, et de Caucaso, qui est ad ortum aestivalem, ex quibus, cum sint maximi montes, multi et maximi fluvii oriuntur; in Europa autem de monte Pyrenaeo, qui est ad occasum aequinoctialem, et de quibusdam aliis montibus qui sunt ad Septentrionem in Scythia, ex quibus etiam fiunt magna flumina; et in Africa, sive in Libya, de quibusdam aliis magnis montibus, ex quibus alia magna flumina fluunt. Et similiter dicit esse de aliis montibus et fluviis: et quod, quicumque alii fluvii fluunt ex paludibus, paludes istae sunt positae prope montes, et sic in idem redit. Et sic, exemplis positis, concludit propositum, dicens: quod quidem igitur non oportet et cetera. Et repetit quod supra dictum est: unde planum est in littera. And this is plain, if one examines a traveler's description of the earth: for those who so described the earth have either themselves seen the rivers and regions, or learned of them from others. He therefore presents first the example of Parnassus which is in Asia at the winter rising [i.e., the southeast], and of the Caucasus, at the summer rising [north east]: since these are very large mountains, many and very large rivers rise from them. In Europe he gives the example of the Pyrenees located in the equinoctial setting [equatorial west], as well as of certain other mountains, which lie toward the north in Scythia: large rivers rise from them too. Then in Africa or in Libya he gives the example of certain other large mountains from which other great rivers flow. And he says the same is true of other mountains and rivers, and that, whatever other rivers flow from marshes, these marshes are located near mountains; and thus is the same thing true. — From these examples, therefore, he concludes to his proposition [127] and repeats what was said above: thus the text is plain.
Deinde cum dicit: non solum sed et talia etc., excludit rationem ponentium praedictam positionem. Et dicit quod non est inconveniens quod inveniantur aliqua loca habentia actu multitudinem aquae, ac si essent stagna; sed non ad tantum hoc valet, ut ex hoc possit accidere fluxus fluviorum. Non enim magis possumus dicere quod aquae, si quae collectae inveniuntur sub terra vel in montibus, contineant totam aquam fluviorum, quam si quis dicat quod fontes qui manifeste apparent extra terram, totam aquam fluviorum actu contineant: plurimi enim fluviorum fluunt ex fontibus (quod dicit propter hoc quod aliqui fluunt ex paludibus, ut dictum est). Unde simile est putare quod contineant totum corpus aquae quae fluit per flumina, illae collectiones subterraneae, ut existimare quod ipsam contineant istae collectiones aquarum quae inveniuntur extra terram in fontibus. Unde, cum de fontibus manifestum sit hoc esse falsum, per simile potest cognosci hoc etiam esse falsum de collectionibus aquarum quae sunt sub terra. Quod autem sint tales collectiones aquarum sub terra, manifestum esse potest per hoc quod multa flumina absorbentur a terra. Et hoc manifestat per multa exempla: et est planum in littera. 130. Then [128] he refutes the argument of those who posit the opinion under discussion. And he says that it is not inadmissible that places should be found actually containing a vast amount of water after the manner of lakes: but this is not sufficient to account for the flow of rivers. For we can no more say that the waters which may exist collected under the earth or in the mountains, contain all the water of rivers, than we can say that the springs, which plainly appear outside the earth, actually contain all the water of rivers: for most rivers flow from springs (which he says, because some flow from marshes, as has been said). Hence to think that those subterranean collections of water contain the entire body of waters that flow through rivers is like supposing that those collections of water found outside the earth in springs contain all the water found in rivers. Hence, since it is plainly false to suppose this of the springs we can see, then it can be known by analogy that it is also false to suppose it of the collections of water under the earth. But that such collections of water do exist under the earth can be made manifest by the fact that many streams are absorbed by the earth. This he explains with many examples that are plain in the text.

Lecture 17
The duration and change of rivers
Chapter 14
οὐκ αἰεὶ δ' οἱ αὐτοὶ τόποι τῆς γῆς οὔτ' ἔνυγροί εἰσιν οὔτε ξηροί, ἀλλὰ μεταβάλλουσιν κατὰ τὰς τῶν ποταμῶν γενέσεις καὶ τὰς ἀπολείψεις διὸ καὶ τὰ περὶ τὴν ἤπειρον μεταβάλλει καὶ τὴν θάλατταν, καὶ οὐκ αἰεὶ τὰ μὲν γῆ τὰ δὲ θάλαττα διατελεῖ πάντα τὸν χρόνον, ἀλλὰ γίγνεται θάλαττα μὲν ὅπου χέρσος, ἔνθα δὲ νῦν θάλαττα, πάλιν ἐνταῦθα γῆ. κατὰ μέντοι τινὰ τάξιν νομίζειν χρὴ ταῦτα γίγνεσθαι καὶ περίοδον. 129 The same parts of the earth are not always moist or dry, but they change according as rivers come into existence and dry up. And so the relation of land to sea changes too and a place does not always remain land or sea throughout all time, but where there was dry land there comes to be sea, and where there is now sea, there one day comes to be dry land. But we must suppose these changes to follow some order and cycle.
ἀρχὴ δὲ τούτων καὶ αἴτιον ὅτι καὶ τῆς γῆς τὰ ἐντός, ὥσπερ τὰ σώματα τῶν φυτῶν καὶ ζῴων, ἀκμὴν ἔχει καὶ γῆρας. πλὴν ἐκείνοις μὲν οὐ κατὰ μέρος ταῦτα συμβαίνει πάσχειν, ἀλλ' ἅμα πᾶν ἀκμάζειν καὶ φθίνειν ἀναγκαῖον τῇ δὲ γῇ τοῦτο γίγνεται κατὰ μέρος διὰ ψύξιν καὶ θερμότητα. ταῦτα μὲν οὖν αὔξεται καὶ φθίνει διὰ τὸν ἥλιον καὶ τὴν περιφοράν, διὰ δὲ ταῦτα καὶ τὴν δύναμιν τὰ μέρη τῆς γῆς λαμβάνει διαφέρουσαν, ὥστε μέχρι τινὸς ἔνυδρα δύναται διαμένειν, εἶτα ξηραίνεται καὶ γηράσκει πάλιν ἕτεροι δὲ τόποι βιώσκονται καὶ ἔνυδροι γίγνονται κατὰ μέρος. ἀνάγκη δὲ τῶν μὲν τόπων γιγνομένων (351b.) ξηροτέρων τὰς πηγὰς ἀφανίζεσθαι, τούτων δὲ συμβαινόντων τοὺς ποταμοὺς πρῶτον μὲν ἐκ μεγάλων μικρούς, εἶτα τέλος γίγνεσθαι ξηρούς, τῶν δὲ ποταμῶν μεθισταμένων καὶ ἔνθεν μὲν ἀφανιζομένων ἐν ἄλλοις δ' ἀνάλογον γιγνομένων μεταβάλλειν τὴν θάλατταν ὅπου μὲν γὰρ ἐξωθουμένη ὑπὸ τῶν ποταμῶν ἐπλεόναζεν, ἀπιοῦσαν ξηρὰν ποιεῖν ἀναγκαῖον, ὅπου δὲ τοῖς ῥεύμασιν πληθύουσα ἐξηραίνετο προσχουμένη, πάλιν ἐνταῦθα λιμνάζειν. 130 The principle and cause of these changes is that the interior of the earth grows and decays, like the bodies of plants and animals. Only in the case of these latter the process does not go on by parts, but each of them necessarily grows or decays as a whole, whereas it does go on by parts in the case of the earth. Here the causes are cold and heat, which increase and diminish on account of the sun and its course. It is owing to them that the parts of the earth come to have a different character, that some parts remain moist for a certain time, and then dry up and grow old, while other parts in their turn are filled with life and moisture. Now when places become drier the springs necessarily give out, and when this happens the rivers first decrease in size and then finally become dry; and when rivers change and disappear in one part and come into existence correspondingly in another, the sea must needs be affected. If the sea was once pushed out by rivers and encroached upon the land anywhere, it necessarily leaves that place dry when it recedes; again, if the dry land has encroached on the sea at all by a process of silting set up by the rivers when at their full, the time must come when this place will be flooded again.
ἀλλὰ διὰ τὸ γίγνεσθαι πᾶσαν τὴν φυσικὴν περὶ τὴν γῆν γένεσιν ἐκ προσαγωγῆς καὶ ἐν χρόνοις παμμήκεσι πρὸς τὴν ἡμετέραν ζωήν, λανθάνει ταῦτα γιγνόμενα, καὶ πρότερον ὅλων τῶν ἐθνῶν ἀπώλειαι γίγνονται καὶ φθοραὶ πρὶν μνημονευθῆναι τὴν τούτων μεταβολὴν ἐξ ἀρχῆς εἰς τέλος. μέγισται μὲν οὖν φθοραὶ γίγνονται καὶ τάχισται ἐν τοῖς πολέμοις, ἄλλαι δὲ νόσοις, αἱ δὲ ἀφορίαις, καὶ ταύταις αἱ μὲν μεγάλαι αἱ δὲ κατὰ μικρόν, ὥστε λανθάνουσι τῶν γε τοιούτων ἐθνῶν καὶ αἱ μεταναστάσεις διὰ τὸ τοὺς μὲν λείπειν τὰς χώρας, τοὺς δὲ ὑπομένειν μέχρι τούτου μέχριπερ ἂν μηκέτι δύνηται τρέφειν ἡ χώρα πλῆθος μηδέν. ἀπὸ τῆς πρώτης οὖν ἀπολείψεως εἰς τὴν ὑστέραν εἰκὸς γίγνεσθαι μακροὺς χρόνους, ὥστε μηδένα μνημονεύειν, ἀλλὰ σῳζομένων ἔτι τῶν ὑπομενόντων ἐπιλελῆσθαι διὰ χρόνου πλῆθος. τὸν αὐτὸν δὲ τρόπον χρὴ νομίζειν καὶ τοὺς κατοικισμοὺς λανθάνειν πότε πρῶτον ἐγένοντο τοῖς ἔθνεσιν ἑκάστοις εἰς τὰ μεταβάλλοντα καὶ γιγνόμενα ξηρὰ ἐξ ἑλωδῶν καὶ ἐνύδρων καὶ γὰρ ἐνταῦθα κατὰ μικρὸν ἐν πολλῷ γίγνεται χρόνῳ ἡ ἐπίδοσις, ὥστε μὴ μνημονεύειν τίνες πρῶτοι καὶ πότε καὶ πῶς ἐχόντων ἦλθον τῶν τόπων, οἷον συμβέβηκεν καὶ τὰ περὶ Αἴγυπτον καὶ γὰρ οὗτος ἀεὶ ξηρότερος ὁ τόπος φαίνεται γιγνόμενος καὶ πᾶσα ἡ χώρα τοῦ ποταμοῦ πρόσχωσις οὖσα τοῦ Νείλου, διὰ δὲ τὸ κατὰ μικρὸν ξηραινομένων τῶν ἑλῶν τοὺς πλησίον εἰσοικίζεσθαι τὸ τοῦ χρόνου μῆκος ἀφῄρηται τὴν ἀρχήν. φαίνεται οὖν καὶ τὰ στόματα πάντα, πλὴν ἑνὸς τοῦ Κανωβικοῦ, χειροποίητα καὶ οὐ τοῦ ποταμοῦ ὄντα, καὶ τὸ ἀρχαῖον ἡ Αἴγυπτος Θῆβαι καλούμεναι. δηλοῖ δὲ καὶ Ὅμηρος, οὕτως πρόσφατος ὢν ὡς εἰπεῖν πρὸς τὰς τοιαύτας μεταβολάς ἐκείνου γὰρ τοῦ τόπου (352a.) ποιεῖται μνείαν ὡς οὔπω Μέμφιος οὔσης ἢ ὅλως ἢ οὐ τηλικαύτης. τοῦτο δ' εἰκὸς οὕτω συμβαίνειν οἱ γὰρ κάτωθεν τόποι τῶν ἄνωθεν ὕστερον ᾠκίσθησαν ἑλώδεις γὰρ ἐπὶ πλείω χρόνον ἀναγκαῖον εἶναι τοὺς ἐγγύτερον τῆς προσχώσεως διὰ τὸ λιμνάζειν ἐν τοῖς ἐσχάτοις ἀεὶ μᾶλλον. μεταβάλλει δὲ τοῦτο καὶ πάλιν εὐθενεῖ ξηραινόμενοι γὰρ οἱ τόποι ἔρχονται εἰς τὸ καλῶς ἔχειν, οἱ δὲ πρότερον εὐκραεῖς ὑπερξηραινόμενοί ποτε γίγνονται χείρους. ὅπερ συμβέβηκε τῆς Ἑλλάδος καὶ περὶ τὴν Ἀργείων καὶ Μυκηναίων χώραν ἐπὶ μὲν γὰρ τῶν Τρωικῶν ἡ μὲν Ἀργεία διὰ τὸ ἑλώδης εἶναι ὀλίγους ἐδύνατο τρέφειν, ἡ δὲ Μυκηναία καλῶς εἶχεν (διὸ ἐντιμοτέρα ἦν), νῦν δὲ τοὐναντίον διὰ τὴν προειρημένην αἰτίαν ἡ μὲν γὰρ ἀργὴ γέγονεν καὶ ξηρὰ πάμπαν, τῆς δὲ τὰ τότε διὰ τὸ λιμνάζειν ἀργὰ νῦν χρήσιμα γέγονεν. ὥσπερ οὖν ἐπὶ τούτου τοῦ τόπου συμβέβηκεν ὄντος μικροῦ, ταὐτὸ δεῖ νομίζειν τοῦτο συμβαίνειν καὶ περὶ μεγάλους τόπους καὶ χώρας ὅλας. 131 But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed. Of such destructions the most utter and sudden are due to wars; but pestilence or famine cause them too. Famines, again, are either sudden and severe or else gradual. In the latter case the disappearance of a nation is not noticed because some leave the country while others remain; and this goes on until the land is unable to maintain any inhabitants at all. So a long period of time is likely to elapse from the first departure to the last, and no one remembers and the lapse of time destroys all record even before the last inhabitants have disappeared. In the same way a nation must be supposed to lose account of the time when it first settled in a land that was changing from a marshy and watery state and becoming dry. Here, too, the change is gradual and lasts a long time and men do not remember who came first, or when, or what the land was like when they came. This has been the case with Egypt. Here it is obvious that the land is continually getting drier and that the whole country is a deposit of the river Nile. But because the neighbouring peoples settled in the land gradually as the marshes dried, the lapse of time has hidden the beginning of the process. However, all the mouths of the Nile, with the single exception of that at Canopus, are obviously artificial and not natural. And Egypt was nothing more than what is called Thebes, as Homer, too, shows, modern though he is in relation to such changes. For Thebes is the place that he mentions; which implies that Memphis did not yet exist, or at any rate was not as important as it is now. That this should be so is natural, since the lower land came to be inhabited later than that which lay higher. For the parts that lie nearer to the place where the river is depositing the silt are necessarily marshy for a longer time since the water always lies most in the newly formed land. But in time this land changes its character, and in its turn enjoys a period of prosperity. For these places dry up and come to be in good condition while the places that were formerly well-tempered some day grow excessively dry and deteriorate. This happened to the land of Argos and Mycenae in Greece. In the time of the Trojan wars the Argive land was marshy and could only support a small population, whereas the land of Mycenae was in good condition (and for this reason Mycenae was the superior). But now the opposite is the case, for the reason we have mentioned: the land of Mycenae has become completely dry and barren, while the Argive land that was formerly barren owing to the water has now become fruitful. Now the same process that has taken place in this small district must be supposed to be going on over whole countries and on a large scale.
οἱ μὲν οὖν βλέποντες ἐπὶ μικρὸν αἰτίαν οἴονται τῶν τοιούτων εἶναι παθημάτων τὴν τοῦ ὅλου μεταβολὴν ὡς γιγνομένου τοῦ οὐρανοῦ διὸ καὶ τὴν θάλατταν ἐλάττω γίγνεσθαί φασιν ὡς ξηραινομένην, ὅτι πλείους φαίνονται τόποι τοῦτο πεπονθότες νῦν ἢ πρότερον. ἔστιν δὲ τούτων τὸ μὲν ἀληθὲς τὸ δ' οὐκ ἀληθές πλείους μὲν γάρ εἰσιν οἱ πρότερον ἔνυδροι νῦν δὲ χερσεύοντες, οὐ μὴν ἀλλὰ καὶ τοὐναντίον πολλαχῇ γὰρ σκοποῦντες εὑρήσουσιν ἐπεληλυθυῖαν τὴν θάλατταν. ἀλλὰ τούτου τὴν αἰτίαν οὐ τὴν τοῦ κόσμου γένεσιν οἴεσθαι χρή γελοῖον γὰρ διὰ μικρὰς καὶ ἀκαριαίας μεταβολὰς κινεῖν τὸ πᾶν, ὁ δὲ τῆς γῆς ὄγκος καὶ τὸ μέγεθος οὐδέν ἐστι δή που πρὸς τὸν ὅλον οὐρανόν 132 Men whose outlook is narrow suppose the cause of such events to be change in the universe, in the sense of a coming to be of the world as a whole. Hence they say that the sea being dried up and is growing less, because this is observed to have happened in more places now than formerly. But this is only partially true. It is true that many places are now dry, that formerly were covered with water. But the opposite is true too: for if they look they will find that there are many places where the sea has invaded the land. But we must not suppose that the cause of this is that the world is in process of becoming. For it is absurd to make the universe to be in process because of small and trifling changes, when the bulk and size of the earth are surely as nothing in comparison with the whole world.
ἀλλὰ πάντων τούτων αἴτιον ὑποληπτέον ὅτι γίγνεται διὰ χρόνων εἱμαρμένων, οἷον ἐν ταῖς κατ' ἐνιαυτὸν ὥραις χειμών, οὕτως περιόδου τινὸς μεγάλης μέγας χειμὼν καὶ ὑπερβολὴ ὄμβρων. αὕτη δὲ οὐκ ἀεὶ κατὰ τοὺς αὐτοὺς τόπους, ἀλλ' ὥσπερ ὁ καλούμενος ἐπὶ Δευκαλίωνος κατακλυσμός καὶ γὰρ οὗτος περὶ τὸν Ἑλληνικὸν ἐγένετο τόπον μάλιστα, καὶ τούτου περὶ τὴν Ἑλλάδα τὴν ἀρχαίαν. αὕτη δ' ἐστὶν ἡ περὶ Δωδώνην καὶ τὸν Ἀχελῷον (352b.) οὗτος γὰρ πολλαχοῦ τὸ ῥεῦμα μεταβέβληκεν ᾤκουν γὰρ οἱ Σελλοὶ ἐνταῦθα καὶ οἱ καλούμενοι τότε μὲν Γραικοὶ νῦν δ' Ἕλληνες. 133 Rather we must take the cause of all these changes to be that, just as winter occurs in the seasons of the year, so in determined periods there comes a great winter of a great year and with it excess of rain. But this excess does not always occur in the same place. The deluge in the time of Deucalion, for instance, took place chiefly in the Greek world and in it especially about ancient Hellas, the country about Dodona and the Achelous, a river which has often changed its course. Here the Selli dwelt and those who were formerly called Graeci and now Hellenes.
ὅταν οὖν γένηται τοιαύτη ὑπερβολὴ ὄμβρων, νομίζειν χρὴ ἐπὶ πολὺν χρόνον διαρκεῖν, καὶ ὥσπερ νῦν τοῦ ἀενάους εἶναί τινας τῶν ποταμῶν τοὺς δὲ μὴ οἱ μέν φασιν αἴτιον εἶναι τὸ μέγεθος τῶν ὑπὸ γῆς χασμάτων, ἡμεῖς δὲ τὸ μέγεθος τῶν ὑψηλῶν τόπων καὶ τὴν πυκνότητα καὶ ψυχρότητα αὐτῶν (οὗτοι γὰρ πλεῖστον καὶ δέχονται ὕδωρ καὶ στέγουσιν καὶ ποιοῦσιν ὅσοις δὲ μικραὶ αἱ ἐπικρεμάμεναι τῶν ὀρῶν συστάσεις ἢ σομφαὶ καὶ λιθώδεις καὶ ἀργιλώδεις, τούτους δὲ προαπολείπειν), οὕτως οἴεσθαι δεῖν τότε, ἐν οἷς ἂν γένηται ἡ τοιαύτη τοῦ ὑγροῦ φορά, οἷον ἀενάους ποιεῖν τὰς ὑγρότητας τῶν τόπων μᾶλλον. τῷ χρόνῳ δὲ ταῦτα ξηραίνεται γιγνόμενα μᾶλλον, θάτερα δ' ἐλάττω τὰ ἔφυδρα, ἕως ἂν ἔλθῃ πάλιν ἡ καταβολὴ τῆς περιόδου τῆς αὐτῆς. ἐπεὶ δ' ἀνάγκη τοῦ ὅλου γίγνεσθαι μέν τινα μεταβολήν, μὴ μέντοι γένεσιν καὶ φθοράν, εἴπερ μένει τὸ πᾶν, ἀνάγκη, καθάπερ ἡμεῖς λέγομεν, μὴ τοὺς αὐτοὺς ἀεὶ τόπους ὑγρούς τ' εἶναι θαλάττῃ καὶ ποταμοῖς καὶ ξηρούς. 134 When, therefore, such an excess of rain occurs we must suppose that it suffices for a long time. We have seen that some say that the size of the subterranean cavities is what makes some rivers perennial and others not, whereas we maintain that the size of the mountains is the cause, and their density and coldness; for great, dense, and cold mountains catch and keep and create most water: whereas if the mountains that overhang the sources of rivers are small or porous and stony and clayey, these rivers run dry earlier. We must recognize the same kind of thing in this case too. Where such abundance of rain falls in the great winter it tends to make the moisture of those places almost everlasting. But as time goes on places of the latter type dry up more, while those of the former, moist type, do so less: until at last the beginning of the same cycle returns. Since there is necessarily some change in the whole world, but not in the way of coming into existence or perishing (for the universe is permanent), it must be, as we say, that the same places are not for ever moist through the presence of sea and rivers, nor for ever dry.
δηλοῖ δὲ τὸ γιγνόμενον οὓς γάρ φαμεν ἀρχαιοτάτους εἶναι τῶν ἀνθρώπων Αἰγυπτίους, τούτων ἡ χώρα πᾶσα γεγονυῖα φαίνεται καὶ οὖσα τοῦ ποταμοῦ ἔργον. καὶ τοῦτο κατά τε τὴν χώραν αὐτὴν ὁρῶντι δῆλόν ἐστιν, καὶ τὰ περὶ τὴν ἐρυθρὰν θάλατταν τεκμήριον ἱκανόν ταύτην γὰρ τῶν βασιλέων τις ἐπειράθη διορύττειν (οὐ γὰρ μικρὰς εἶχεν ἂν αὐτοῖς ὠφελείας πλωτὸς πᾶς ὁ τόπος γενόμενος λέγεται δὲ πρῶτος Σέσωστρις ἐγχειρῆσαι τῶν παλαιῶν), ἀλλ' εὗρεν ὑψηλοτέραν οὖσαν τὴν θάλατταν τῆς γῆς διὸ ἐκεῖνός τε πρότερον καὶ Δαρεῖος ὕστερον ἐπαύσατο διορύττων, ὅπως μὴ διαφθαρῇ τὸ ῥεῦμα τοῦ ποταμοῦ συμμιγείσης τῆς θαλάττης. φανερὸν οὖν ὅτι θάλαττα πάντα μία ταύτῃ συνεχὴς ἦν. διὸ καὶ τὰ περὶ τὴν Λιβύην τὴν Ἀμμωνίαν χώραν ταπεινότερα φαίνεται καὶ κοιλότερα παρὰ λόγον τῆς κάτωθεν χώρας δῆλον γὰρ ὡς ἐγχώσεως μὲν γενομένης ἐγένοντο λίμναι καὶ χέρσος, χρόνου δὲ γενομένου τὸ ἐναπολειφθὲν καὶ λιμνάσαν ὕδωρ (353a.) ξηρανθέν ἐστιν ἤδη φροῦδον. ἀλλὰ μὴν καὶ τὰ περὶ τὴν Μαιῶτιν λίμνην ἐπιδέδωκε τῇ προσχώσει τῶν ποταμῶν τοσοῦτον, ὥστε πολλῷ ἐλάττω μεγέθει πλοῖα νῦν εἰσπλεῖν πρὸς τὴν ἐργασίαν ἢ ἔτος ἑξηκοστόν ὥστε ἐκ τούτου ῥᾴδιον ἀναλογίσασθαι ὅτι καὶ τὸ πρῶτον, ὥσπερ αἱ πολλαὶ τῶν λιμνῶν, καὶ αὕτη ἔργον ἐστὶ τῶν ποταμῶν, καὶ τὸ τελευταῖον πᾶσαν ἀνάγκη γενέσθαι ξηράν. ἔτι δὲ ὁ Βόσπορος ἀεὶ μὲν ῥεῖ διὰ τὸ προσχοῦσθαι, καὶ ἔστιν ἔτι ταῦτα καὶ τοῖς ὄμμασιν ἰδεῖν ὅν τινα συμβαίνει τρόπον ὅτε γὰρ ἀπὸ τῆς Ἀσίας ᾐόνα ποιήσειεν ὁ ῥοῦς, τὸ ὄπισθεν λίμνη ἐγίγνετο μικρὰ τὸ πρῶτον, εἶτ' ἐξηράνθη ἄν, μετὰ δὲ τοῦτο ἄλλη ἡ ἀπὸ ταύτης ᾐών, καὶ λίμνη ἀπὸ ταύτης καὶ τοῦτο ἀεὶ οὕτως συνέβαινεν ὁμοίως τούτου δὲ γιγνομένου πολλάκις ἀνάγκη χρόνου προϊόντος ὥσπερ ποταμὸν γενέσθαι, τέλος δὲ καὶ τοῦτον ξηρόν. 135 And the facts prove this. The whole land of the Egyptians, whom we take to be the most ancient of men, has evidently gradually come into existence and been produced by the river. This is clear from an observation of the country, and the facts about the Red Sea suffice to prove it too. One of their kings tried to make a canal to it (for it would have been of no little advantage to them for the whole region to have become navigable; Sesostris is said to have been the first of the ancient kings to try), but he found that the sea was higher than the land. So he first, and Darius afterwards, stopped making the canal, lest the sea should mix with the river water and spoil it. So it is clear that all this part was once unbroken sea. For the same reason Libya—the country of Ammon—is, strangely enough, lower and hollower than the land to the seaward of it. For it is clear that a barrier of silt was formed and after it lakes and dry land, but in course of time the water that was left behind in the lakes dried up and is now all gone. Again the silting up of the lake Maeotis by the rivers has advanced so much that the limit to the size of the ships which can now sail into it to trade is much lower than it was sixty years ago. Hence it is easy to infer that it, too, like most lakes, was originally produced by the rivers and that it must end by drying up entirely. Again, this process of silting up causes a continuous current through the Bosporus; and in this case we can directly observe the nature of the process. Whenever the current from the Asiatic shore threw up a sandbank, there first formed a small lake behind it. Later it dried up and a second sandbank formed in front of the first and a second lake. This process went on uniformly and without interruption. Now when this has been repeated often enough, in the course of time the strait must become like a river, and in the end the river itself must dry up.
φανερὸν τοίνυν, ἐπεὶ ὅ τε χρόνος οὐχ ὑπολείψει καὶ τὸ ὅλον ἀίδιον, ὅτι οὔτε ὁ Τάναϊς οὔτε ὁ Νεῖλος ἀεὶ ἔρρει, ἀλλ' ἦν ποτε ξηρὸς ὁ τόπος ὅθεν ῥέουσιν τὸ γὰρ ἔργον ἔχει αὐτῶν πέρας, ὁ δὲ χρόνος οὐκ ἔχει. ὁμοίως δὲ τοῦτο καὶ ἐπὶ τῶν ἄλλων ἁρμόσει ποταμῶν λέγειν. ἀλλὰ μὴν εἴπερ καὶ οἱ ποταμοὶ γίγνονται καὶ φθείρονται καὶ μὴ ἀεὶ οἱ αὐτοὶ τόποι τῆς γῆς ἔνυδροι, καὶ τὴν θάλατταν ἀνάγκη μεταβάλλειν ὁμοίως. τῆς δὲ θαλάττης τὰ μὲν ἀπολειπούσης τὰ δ' ἐπιούσης ἀεὶ φανερὸν ὅτι τῆς πάσης γῆς οὐκ ἀεὶ τὰ αὐτὰ τὰ μέν ἐστιν θάλαττα τὰ δ' ἤπειρος, ἀλλὰ μεταβάλλει τῷ χρόνῳ πάντα. 136 So it is clear, since there will be no end to time and the world is eternal, that neither the Tanais nor the Nile has always been flowing, but that the region whence they flow was once dry: for their effect may be fulfilled, but time cannot. And this will be equally true of all other rivers. But if rivers come into existence and perish and the same parts of the earth were not always moist, the sea must needs change correspondingly. And if the sea is always advancing in one place and receding in another it is clear that the same parts of the whole earth are not always either sea or land, but that all this changes in course of time.
διότι μὲν οὖν οὐκ ἀεὶ ταὐτὰ οὔτε χερσεύει τῆς γῆς οὔτε πλωτά ἐστιν, καὶ διὰ τίν' αἰτίαν ταῦτα συμβαίνει, εἴρηται ὁμοίως δὲ καὶ διὰ τί οἱ μὲν ἀέναοι οἱ δ' οὒ τῶν ποταμῶν εἰσιν. 137 So we have explained that the same parts of the earth are not always land or sea and why that is so: and also why some rivers are perennial and others not.
Postquam philosophus ostendit causam generationis fluviorum, hic determinat de duratione eorum. Et circa hoc duo facit. 131. After showing the cause of the generation of rivers, the Philosopher here determines about their duration. About this he does two things:
Primo ponit opinionem suam circa hoc. Et dicit quod non semper eadem loca terrae sunt aquosa vel arida; sed hoc permutatur secundum quod fluvii generantur de novo vel deficiunt. Propter quam causam fit permutatio circa terram, ut quae nunc est arida, aliquando fiat mare, et e converso; et non semper in una et eadem parte terrae sint mare vel terra sicca. Sed hoc non accidit casu, sed secundum quendam ordinem, et secundum aliquam circulationem caeli; sicut et omnes transmutationes quae fiunt in istis inferioribus, ordinantur secundum motum caeli. First, he presents his own opinion [129] and says that the same parts of the earth are not always moist or dry, but they vary according as rivers are newly formed or decay. As a result, changes occur affecting the earth, so that what is now dry, later becomes a sea and vice versa; and sea or dry land are not always present in the same part of the earth. But this takes place, not by chance, but according to a certain order and according to a certain turning of the heavens, just as all changes taking place in these lower regions are regulated according to the movement of the heaven.
Secundo ibi: principium autem etc., manifestat quod dixerat. Et circa hoc duo facit: 132. Secondly [130], he explains what he has said. About this he does two things:

primo assignat causam unam eius quod dictum est;

secundo excludit quandam causam ab aliis opinatam, ibi: qui quidem igitur respiciunt et cetera.

First, he assigns one cause of what has been said, at 132;

Secondly, he rejects a cause held by others, at 134.

Circa primum duo facit: About the first he does two things:

primo assignat causam praedictae transmutationis;

secundo assignat causam quare praedicta transmutatio lateat, ibi: sed propterea quod fit et cetera.

First, he assigns the cause of the transmutation just mentioned, at 132;

Secondly, he explains why such transmutations escape our notice, at 133.

Dicit ergo primo quod causa et principium transmutationis praedictae hoc est, quod virtus terrae habet suo modo statum et senectutem, sicut corpora animalium et plantarum. In hoc tamen est differentia, quod animalia et plantae patiuntur statum et senectutem, non successive secundum diversas partes, sed simul secundum totum: sed in terra haec transmutatio est secundum partem et partem, propter caliditatem et frigus, crescente una parte in caliditate vel frigore, et alia deminuta, propter motum solis et alias circulationes caelestium corporum. secundum totum in terra, sicut in animalibus et plantis; sed secundum partem et partem. He says therefore first [130], that the cause and source of the above-mentioned transmutation is that the energy of the earth has its own kind of coming to a stop and old age, just as do bodies of animals and plants. But there is this difference: animals and plants suffer a stopping and old age, not successively with respect to different parts, but all at one time with respect to the whole, while, in the earth, this change is part by part, depending on the influence of heat and cold — for one part increases in heat or coldness, while another decreases, depending on the course of the sun and on other cycles of the heavenly bodies.
Et inde est quod secundum diversum situm in aspectu solis et stellarum, partes terrae recipiunt diversam virtutem; ita quod aliquae partes terrae possunt diu permanere in humiditate et aquositate, secundum aliquod determinatum tempus, quod est eis quasi iuventus vel status; et postmodum siccari, quod est terrae quasi senectus, quae naturaliter propter defectum humorum habet desiccare. Et dum hae partes terrae exsiccantur, alia loca terrae vivificantur, et fiunt aquosa secundum aliquam partem. Quod patet per hoc, quia in vere omnia quasi iuvenescunt per humiditatem; quae in hieme postea senescunt propter nimiam siccitatem. Et in vere etiam nostrae partes terrae sunt in vigore, alibi vero sunt iam desiccata omnia. Et sic patet quod senectus et iuventus non accidunt Hence, depending on their differing position as to the aspects toward the sun and stars, the parts of the earth receive diverse power. As a result, some parts of the earth can continue being moist and watery for a long time according to a definite period — and this is, as it were, their youth or full state; later, they dry up and exist in what is for the earth old age, which naturally is accompanied by dryness, because of the absence of moisture. While these portions of the earth are drying up, other regions of earth are being vivified and become in part watery. This is indicated by the fact that in the spring of the year all things become, so to speak, young again by moisture; but in winter the same things grow old because of the excessive dryness. Moreover, in spring our part of the earth is alive, while elsewhere everything is already dried up. From this it is plain that old age and youth do not affect the earth as a whole (as animals and plants are affected) but one part at a time.
Sic igitur in aliquibus partibus terrae, desiccatae modo praedicto fontes destruuntur: et ex hoc sequitur quod fluvii primo quidem ex magnis rediguntur in parvos, et tandem totaliter exsiccantur, propter siccitatem fontium ex quibus oriebantur. Et sic in una parte terrae, quae iam senuit, exsiccantur; in alia autem, quae facta est aquosa, proportionaliter de novo fiunt fontes et flumina. Et ita facta transmutatione circa flumina, ut scilicet in una parte terrae deficiant et in alia de novo esse incipiant, transmutatur per consequens mare; et ubi abundaverat primo per excrescentiam fluviorum, siccatis fluviis, recedit mare et remanet arida; ubi vero mare exsiccabatur per aliquam atterrationem causatam ex aliquibus fluxibus supervenientibus terrae, iterum ibidem stagnat, aquae abundantia congregata. According to this, therefore, in certain areas of the earth, the springs that are dried up in this way cease to function. As a result, rivers that were once large become small, and finally dry up entirely; because the springs from which they originated are dry. Thus, in one part of the earth now grown old, the springs are dry, but in another part that has become watery, a corresponding number of new springs and rivers arise. Hence, because of these changes which affect streams, so that in one portion of the earth they perish and in another portion new ones arise, the sea too is changed as a consequence. Once the rivers dry up, the sea falls back and dry land appears where the sea was once swollen by the overflow of rivers. But where the sea has been dried up by accretions of earth deposited by rivers, it again is under water when a quantity of water has gathered.
Secundo ibi: sed propterea quod fit etc., assignat rationem quare praedictae transmutationes latent. Et dicit quod praedictae transmutationes maris et aridae latent, quia omnis naturalis transmutatio non fit subito, sed successive; et praedictae transmutationes, quae accidunt circa magnas partes terrae, fiunt in temporibus longissimis; et prius fit interitus et corruptio omnium gentium, quam maneat memoria transmutationis talis a sui principio usque in finem. Si enim semper eaedem gentes remanerent in eisdem partibus terrae, posset remanere aliqua memoria rerum etiam antiquissimarum, et transmutationum: sed quando aliqua gens deletur, et supervenit nova in locum eius, non remanet in secunda gente memoria antiquitatum quae fuerunt in prima gente; et multo minus in tertia vel quarta. 133. Secondly [131], he explains why these transmutations escape our notice, and says that these transmutations of sea and dry land escape us, because every natural change takes place not all at once but bit by bit — and the transmutations under discussion, which affect large sectors of the earth occur over long periods of time; and all nations die and pass away before a memory remains of such a change from its beginning to its end. For if the same peoples always remained in the same areas of the earth, some remembrance, even of things most ancient and of transmutations, could remain — but when one people is destroyed and a new one inhabits their land, no memory of the antiquities of the first remains among the second, much less among the third and fourth.
Corruptiones autem gentium quae novissimae sunt, fiunt per praelia, aliae autem fiunt per infirmitates et epidemias, aliae autem per sterilitates; et harum corruptionum quaedam sunt magnae simul, quaedam vero fiunt paulatim; ut etiam transmutationes gentium de loco ad locum lateant, eo quod aliqui a principio, ex eo quod incipit terra fieri sterilis vel infirma, vel propter guerras, relinquunt regionem, alii autem permanent quandiu possunt ibi nutriri; ita quod a primo discessu usque ad ultimum, quandoque est magnum tempus, et non est memoria primi recessus, etiam si homines non moriantur sed transmigrant. Et sicuti est de desertione terrarum, ita etiam est de habitatione earum: quia non est memoria, propter longinquitatem temporis, quando et a quibus gentibus primo inhabitari coeperunt, et quando sunt immutata ex paludosis in siccitatem, ut habitari possint; quia hoc paulatim factum est et in multo tempore. Et ponit exemplum de terra Aegypti, quae paulatim exsiccata est quasi a fluvio; et de quibusdam aliis terris, quae sunt transmutatae et desiccatae ab aquositate, et e converso; et est planum in littera. Now the disappearances of nations closest to our times are brought on by wars, but some also by diseases and epidemics, and some by sterility: of these destructions some occur all at once on a large scale, and some gradually. Furthermore, the migrations of peoples from place to place go unnoticed, because some forsake a region from the start because the earth is becoming barren or weak, or because of wars; while others remain as long as they can find sustenance there. Hence, the time between the first departure and the last is sometimes long, and there is no memory of the first migration, even if the men do not die, but migrate. And as it is with forsaking lands, so with their settling: because of the length of time, there is no record when and by which races the land first began to be settled and when it was first changed from swamp into dry land and made habitable — this taking place little by little and over long periods of time. And he gives the example of Egypt, whose land was gradually drained dry, as though by the river. He mentions other lands, too, that have been transmuted and drained dry of moisture, and vice versa, as is plain in the text.
Deinde cum dicit: qui quidem igitur respiciunt etc., excludit causam a quibusdam opinatam. Et circa hoc tria facit. Primo excludit causam falsam. Et dicit quod aliqui, respicientes ad aliquid modicum, volunt iudicare de toto caelo: putant enim causam talium transmutationum esse mutationem totius mundi, ac si caelum et mundus de novo sit generatus. Et ex hac causa dicunt quod mare est minoratum, quia a principio coepit desiccari a sole: unde plura loca apparent modo desiccata, quae prius non erant. Sed hoc partim est verum, partim non. Quod enim aliqua loca sint desiccata, quae erant prius aquosa, verum est: licet etiam contrarium verum sit, quia in aliquibus locis invenitur supervenisse mare ubi prius erat arida. Sed hoc est falsum, quod causa huius transmutationis sit mundi generatio. Derisibile enim videtur ponere transmutationem in toto, propter transmutationes in parvis partibus; magnitudo autem terrae quasi nihil est in comparatione ad totum caelum; obtinet enim vicem puncti. 134. Then [132] he dismisses an explanation that some have suggested. About this he does three things: first, he dismisses the false explanation and says that some, by looking at some slight thing, want to make a judgment about the entire heaven: for they think that the cause of such transmutation is that the whole world is changing in the sense that the heaven and the world are being newly formed. They say that the sea gets smaller, because it was beginning to be dried up by the sun from the very beginning: that is why many places formerly moist are now dry. But this is partly true, partly not. For it is true that certain places formerly tilled with water are now dried out; but the opposite is also true, because in some places the sea is found to have invaded areas that were formerly dry land. But it is false that the cause of this change is due to a generation of the earth. For it is ridiculous to postulate transmutations in the whole because of transmutations in small areas. Moreover, the size of the earth is almost as nothing compared with the heaven as a whole, for it takes on the status of a point.
Secundo ibi: sed horum omnium etc., resumit veram causam. Et dicit quod vera causa istarum transmutationum est quod, sicut unus annus dividitur per diversa tempora, scilicet per hiemem et aestatem et consueta, sic et magna aliqua circulatio dividitur secundum statuta tempora, per magnam hiemem, in qua est multus excessus imbrium, et magnam aestatem, in qua est siccitas magna: non autem ita quod simul fiat iste magnus excessus imbrium vel siccitatis secundum totam terram, vel semper secundum easdem partes, sed in diversis partibus. Et ponit exemplum de diluvio facto tempore Deucalionis, in quadam determinata parte Graeciae. 135. Secondly [133], he restates the true cause, and says that the true cause of those transmutations is this: just as a year is divided by different seasons, namely, by winter and summer and the customary seasons, so also a certain great cycle is divided according to established sequences by a great winter, wherein there is an excess of storms, and a great summer, in which there is excessive dryness; but not in the sense that these great excesses of storms and dryness occur at the same time over the entire earth or always over the same regions: they occur in different regions. And he gives the example of the deluge in one definite region of Greece in the time of Deucalion.
Tertio ibi: cum igitur talis factus fuerit etc., assignat ex praedictis causam diuturnitatis fluviorum. Et dicit quod cum in aliqua terra factus fuerit magnus excessus imbrium, ita imbibitur terra humiditate, quod sufficit ad multum tempus ad generationem fluviorum. Quod quidem commune est diversis opinionibus: sive dicatur quod perpetuitas fluviorum est ex magnitudine voraginum continentium multam aquam, ut quidam dicunt, sicut praedictum est; sive dicatur, secundum nostram opinionem superius positam, quod causa perpetuitatis fluviorum est magnitudo et spissitudo et frigiditas altorum locorum, ita quod huiusmodi loca possunt recipere multam aquam, et continere eam, et generare. Sed illa loca in quibus sunt parvae substantiae montium et non multum elevatae in altum, aut sunt quasi spongiosae, ut non possit in eis conservari humiditas, et sunt lapidosae, ut non possint recipere aquam, et sunt argillosae, ut non possint eam generare: in talibus, inquam, locis deficit fluxus fluviorum, quoadusque iterum loca humectentur. Sic ergo oportet putare quod in quibuscumque locis advenerit abundantia imbrium in magna hieme, humiditates locorum erunt magis perpetuae, idest diuturnae. Sed tamen tempore procedente exsiccantur, et quaedam eorum fiunt minus humida, donec iterum revertatur periodus secundum quam fiat excessus imbrium. 136. Thirdly [134], from the foregoing he assigns a cause why rivers last, and says that when excessive storms occur in some region, the earth is saturated with enough moisture to generate rivers for a long time. This is a detail common to various explanations: whether the perpetuity of rivers is explained by large subterranean depths containing much water, as claimed by some, as cited earlier; or whether, according to our own opinion already given, the cause of their perpetuity is the size and thickness and coldness of mountains, by which they can receive and contain vast stores of water as well as generate it. But those places where the substance of the mountains is small and they are not very high, or where they are, so to speak, spongy [porous] so that moisture cannot be preserved in them, and are rocky, so as not to be able to receive water, and are clayey, so as not to be able to generate it, in such places, I say, the flow of rivers diminishes until the region again becomes moist. Therefore, one must believe that in whatever places an abundance of water falls during a great winter, the moisture of such places will be more "perpetual," i.e., long-lasting. Yet, as time goes on, such places dry up and some become less moist until the return again of that period in which there is an excess of rain.
Et sic ultimo concludit quod, quia in toto universo necesse est fieri permutationem; non tamen ita quod generetur et corrumpatur, si totus mundus est perpetuus; necesse est, sicut dictum est, quod non semper eadem loca sint humida per mare vel flumina, aut etiam sicca; sed quae prius fuerunt humida, fiunt sicca, et e converso. And so he concludes finally that, since change must take place in the whole universe (but not in the sense that the whole comes into being and is destroyed), if the world as a whole is perpetual, then it is necessary, as was said, that the same places be not forever moist, because of the sea or rivers, or dry, either — but places that previously were wet, become dry, and vice versa.
Deinde cum dicit: manifestat autem quod etc., manifestat quod dictum est, per exempla. Et circa hoc tria facit. Primo ponit tria exempla. Quorum primum est de terra Aegypti, quae invenitur demissior mari circumstante: propter quam causam impediti sunt quidam reges ne coniungerent duo maria, videntes per hoc destrui fluxum fluvii. 137. Then [135] he manifests what he has said with examples. About this he does three things: First, he gives three examples, the first of which concerns the land of Egypt, which is found to be below the surrounding sea; for this reason certain of their kings were hindered from linking the two seas, when they saw that this would destroy the flow of the river water.
Secundum exemplum est de Maeotide palude, in qua, propter fluxus fluviorum, semper maior atteratio facta est: ita quod poterat ferre multo minores naves tempore suo, quam ante sexaginta annos. The second example concerns Lake Maeotis [Sea of Azov], in which the river flow produces so much silt that in his time it could only take boats much smaller than 60 years earlier.
Tertium exemplum est de Bosphoro dividente Europam ab Asia, qui invenitur minoratus et semper tendens in angustum, propter eandem causam. The third example concerns the Bosphorus, which divides Europe from Asia. This strait is found smaller, and always tending to narrow, for the same reason.
Secundo ibi: manifestum igitur etc., inducit conclusionem principaliter intentam: dicens quod, ex quo tempus non deficit et totum universum est aeternum (quod dicit secundum opinionem suam positam in libro physicorum et de caelo et mundo), sequitur quod neque Tanais neque Nilus, qui sunt maximi fluvii, semper fluxerunt, sed aliquando locus unde fluunt erat siccus: quia opus eorum, scilicet fluxus ipsorum, habet terminum. Et similiter est in aliis fluviis. Et si hoc est de fluviis, oportet quod idem sit de mari, in quod intrant fluvii: et sic secundum diversa tempora permutatur mare et arida. 138. Secondly [136], he draws the conclusion that was chiefly intended and says that since there is no end to time and since the entire universe is eternal (according to his opinion presented in the Physics and in On the Heavens) it follows that neither the Tanais [Don] nor the Nile, which are very large rivers, have always been flowing, but the place whence they flow was once dry: because their "work," i.e., their flow, has a limit. The same is true of other rivers. And if this is true of rivers, it must be true also of the sea into which rivers flow: that is why, at different times, sea and dry land are reversed.
Hoc tamen quod supponit mundum et tempus aeternum, est erroneum et alienum a fide; nec rationes quibus hoc probavit, sunt demonstrationes, ut alibi est ostensum. However, his supposition that the world and time are eternal is erroneous and opposed to the faith; nor are the arguments used to support these suppositions, demonstrations, as was shown elsewhere.
Tertio ibi: quia quidem igitur, recapitulat quod dixerat: et est planum in littera. Thirdly [137], he summarizes what he has said, and the text is clear.


Lecture 1
Opinions of the ancients on the origin of the sea and of its saltiness
Chapter 1
Περὶ δὲ θαλάττης, καὶ τίς ἡ φύσις αὐτῆς, καὶ διὰ τίν' αἰτίαν ἁλμυρὸν τοσοῦτόν ἐστιν ὕδατος πλῆθος, ἔτι δὲ περὶ τῆς ἐξ ἀρχῆς γενέσεως λέγωμεν. 138 Let us explain the nature of the sea and the reason why such a large mass of water is salt and the way in which it originally came to be.
οἱ μὲν οὖν ἀρχαῖοι καὶ διατρίβοντες περὶ τὰς θεολογίας ποιοῦσιν αὐτῆς πηγάς, ἵν' (353b.) αὐτοῖς ὦσιν ἀρχαὶ καὶ ῥίζαι γῆς καὶ θαλάττης τραγικώτερον γὰρ οὕτω καὶ σεμνότερον ὑπέλαβον ἴσως εἶναι τὸ λεγόμενον, ὡς μέγα τι τοῦ παντὸς τοῦτο μόριον ὄν καὶ τὸν λοιπὸν οὐρανὸν ὅλον περὶ τοῦτον συνεστάναι τὸν τόπον καὶ τούτου χάριν ὡς ὄντα τιμιώτατον καὶ ἀρχήν. 139 The old writers who invented theogonies say that the sea has springs, for they want earth and sea to have foundations and roots of their own. Presumably they thought that this view was grander and more impressive as implying that our earth was an important part of the universe. For they believed that the whole world had been built up round our earth and for its sake, and that the earth was the most important and primary part of it.
οἱ δὲ σοφώτεροι τὴν ἀνθρωπίνην σοφίαν ποιοῦσιν αὐτῆς γένεσιν εἶναι γὰρ τὸ πρῶτον ὑγρὸν ἅπαντα τὸν περὶ τὴν γῆν τόπον, ὑπὸ δὲ τοῦ ἡλίου ξηραινόμενον τὸ μὲν διατμίσαν πνεύματα καὶ τροπὰς ἡλίου καὶ σελήνης φασὶ ποιεῖν, τὸ δὲ λειφθὲν θάλατταν εἶναι διὸ καὶ ἐλάττω γίγνεσθαι ξηραινομένην οἴονται, καὶ τέλος ἔσεσθαί ποτε πᾶσαν ξηράν. ἔνιοι δ' αὐτῶν θερμαινομένης φασὶν ὑπὸ τοῦ ἡλίου τῆς γῆς οἷον ἱδρῶτα γίγνεσθαι διὸ καὶ ἁλμυρὰν εἶναι καὶ γὰρ ὁ ἱδρὼς ἁλμυρός. οἱ δὲ τῆς ἁλμυρότητος αἰτίαν τὴν γῆν εἶναί φασιν καθάπερ γὰρ τὸ διὰ τῆς τέφρας ἠθούμενον ἁλμυρὸν γίγνεται, τὸν αὐτὸν τρόπον καὶ ταύτην ἁλμυρὰν εἶναι μειχθείσης αὐτῇ τοιαύτης γῆς. 140 Others, wiser in human knowledge, give an account of its origin. At first, they say, the earth was surrounded by moisture. Then the sun began to dry it up, part of it evaporated and is the cause of winds and the turnings back of the sun and the moon, while the remainder forms the sea. So the sea is being dried up and is growing less, and will end by being some day entirely dried up. Others say that the sea is a kind of sweat exuded by the earth when the sun heats it, and that this explains its saltness: for all sweat is salt. Others say that the saltness is due to the earth. Just as water strained through ashes becomes salt, so the sea owes its saltness to the admixture of earth with similar properties.
ὅτι μὲν οὖν πηγὰς τῆς θαλάττης ἀδύνατον εἶναι, διὰ τῶν ὑπαρχόντων ἤδη θεωρεῖν δεῖ. τῶν γὰρ περὶ τὴν γῆν ὑδάτων τὰ μὲν ῥυτὰ τυγχάνει ὄντα τὰ δὲ στάσιμα. τὰ μὲν οὖν ῥυτὰ πάντα πηγαῖα περὶ δὲ τῶν πηγῶν εἰρήκαμεν πρότερον ὅτι δεῖ νοεῖν οὐχ ὥσπερ ἐξ ἀγγείου ταμιευόμενον τὴν ἀρχὴν εἶναι πηγήν, ἀλλ' εἰς ἓν ἀεὶ γιγνόμενον καὶ συρρέον ἀπαντᾶν πρώτην. τῶν δὲ στασίμων τὰ μὲν συλλογιμαῖα καὶ ὑποστάσεις, οἷον τὰ τελματιαῖα καὶ ὅσα λιμνώδη, πλήθει καὶ ὀλιγότητι διαφέροντα, τὰ δὲ πηγαῖα. ταῦτα δὲ πάντα χειρόκμητα, λέγω δ' οἷον τὰ φρεατιαῖα καλούμενα πάντων γὰρ ἀνωτέρω δεῖ τὴν πηγὴν εἶναι τῆς ῥύσεως. διὸ τὰ μὲν αὐτόματα ῥεῖ τὰ κρηναῖα καὶ ποτάμια, ταῦτα δὲ τέχνης προσδεῖται τῆς ἐργασομένης. αἱ μὲν οὖν διαφοραὶ τοσαῦται καὶ τοιαῦται τῶν ὑδάτων εἰσίν τούτων δ' οὕτω διωρισμένων ἀδύνατον πηγὰς εἶναι τῆς θαλάττης ἐν οὐδετέρῳ γὰρ τούτων οἷόν τ' εἶναι τῶν γενῶν αὐτήν οὔτε γὰρ ἀπόρρυτός ἐστιν οὔτε χειροποίητος, τὰ δὲ πηγαῖα πάντα τούτων θάτερον πέπονθεν αὐτόματον δὲ στάσιμον τοσοῦτον πλῆθος οὐδὲν ὁρῶμεν πηγαῖον γιγνόμενον. 141 We must now consider the facts which prove that the sea cannot possibly have springs. The waters we find on the earth either flow or are stationary. All flowing water has springs. (By a spring, as we have explained above, we must not understand a source from which waters are ladled as it were from a vessel, but a first point at which the water which is continually forming and percolating gathers.) Stationary water is either that which has collected and has been left standing, marshy pools, for instance, and lakes, which differ merely in size, or else it comes from springs. In this case it is always artificial, I mean as in the case of wells, otherwise the spring would have to be above the outlet. Hence the water from fountains and rivers flows of itself, whereas wells need to be worked artificially. All the waters that exist belong to one or other of these classes. On the basis of this division we can see that the sea cannot have springs. For it falls under neither of the two classes; it does not flow and it is not artificial; whereas all water from springs must belong to one or other of them. Natural standing water from springs is never found on such a large scale.
ἔτι δ' ἐπεὶ πλείους εἰσὶ (354a.) θάλατται πρὸς ἀλλήλας οὐ συμμειγνύουσαι κατ' οὐδένα τόπον, ὧν ἡ μὲν ἐρυθρὰ φαίνεται κατὰ μικρὸν κοινωνοῦσα πρὸς τὴν ἔξω στηλῶν θάλατταν, ἡ δ' Ὑρκανία καὶ Κασπία κεχωρισμέναι τε ταύτης καὶ περιοικούμεναι κύκλῳ, ὥστ' οὐκ ἂν ἐλάνθανον αἱ πηγαί, εἰ κατά τινα τόπον αὐτῶν ἦσαν. 142 Again, there are several seas that have no communication with one another at all. The Red Sea, for instance, communicates but slightly with the ocean outside the straits, and the Hyrcanian and Caspian seas are distinct from this ocean and people dwell all round them. Hence, if these seas had had any springs anywhere they must have been discovered.
ῥέουσα δ' ἡ θάλαττα φαίνεται κατά τε τὰς στενότητας, εἴ που διὰ τὴν περιέχουσαν γῆν εἰς μικρὸν ἐκ μεγάλου συνάγεται πελάγους, διὰ τὸ ταλαντεύεσθαι δεῦρο κἀκεῖσε πολλάκις. τοῦτο δ' ἐν μὲν πολλῷ πλήθει θαλάττης ἄδηλον ᾗ δὲ διὰ τὴν στενότητα τῆς γῆς ὀλίγον ἐπέχει τόπον, ἀναγκαῖον τὴν ἐν τῷ πελάγει μικρὰν ταλάντωσιν ἐκεῖ φαίνεσθαι μεγάλην. ἡ δ' ἐντὸς Ἡρακλείων στηλῶν ἅπασα κατὰ τὴν τῆς γῆς κοιλότητα ῥεῖ, καὶ τῶν ποταμῶν τὸ πλῆθος ἡ μὲν γὰρ Μαιῶτις εἰς τὸν Πόντον ῥεῖ, οὗτος δ' εἰς τὸν Αἰγαῖον. τὰ δ' ἤδη τούτων ἔξω πελάγη ἧττον ποιεῖ τοῦτ' ἐπιδήλως. ἐκείνοις δὲ διά τε τὸ τῶν ποταμῶν πλῆθος συμβαίνει τοῦτο (πλείους γὰρ εἰς τὸν Εὔξεινον ῥέουσιν ποταμοὶ καὶ τὴν Μαιῶτιν ἢ τὴν πολλαπλασίαν χώραν αὐτῆς) καὶ διὰ τὴν βραχύτητα τοῦ βάθους ἀεὶ γὰρ ἔτι βαθυτέρα φαίνεται οὖσα ἡ θάλαττα, καὶ τῆς μὲν Μαιώτιδος ὁ Πόντος, τούτου δ' ὁ Αἰγαῖος, τοῦ δ' Αἰγαίου ὁ Σικελικός ὁ δὲ Σαρδονικὸς καὶ Τυρρηνικὸς βαθύτατοι πάντων. τὰ δ' ἔξω στηλῶν βραχέα μὲν διὰ τὸν πηλόν, ἄπνοα δ' ἐστὶν ὡς ἐν κοίλῳ τῆς θαλάττης οὔσης. ὥσπερ οὖν καὶ κατὰ μέρος ἐκ τῶν ὑψηλῶν οἱ ποταμοὶ φαίνονται ῥέοντες, οὕτω καὶ τῆς ὅλης γῆς ἐκ τῶν ὑψηλοτέρων τῶν πρὸς ἄρκτον τὸ ῥεῦμα γίγνεται τὸ πλεῖστον ὥστε τὰ μὲν διὰ τὴν ἔκχυσιν οὐ βαθέα, τὰ δ' ἔξω πελάγη βαθέα μᾶλλον. 143 It is true that in straits, where the land on either side contracts an open sea into a small space, the sea appears to flow. But this is because it is swinging to and fro. In the open sea this motion is not observed, but where the land narrows and contracts the sea the motion that was imperceptible in the open necessarily strikes the attention. The whole of the Mediterranean does actually flow. The direction of this flow is determined by the depth of the basins and by the number of rivers. Maeotis flows into Pontus and Pontus into the Aegean. After that the flow of the remaining seas is not so easy to observe. The current of Maeotis and Pontus is due to the number of rivers (more rivers flow into the Euxine and Maeotis than into the whole Mediterranean with its much larger basin), and to their own shallowness. For we find the sea getting deeper and deeper. Pontus is deeper than Maeotis, the Aegean than Pontus, the Sicilian sea than the Aegean; the Sardinian and Tyrrhenic being the deepest of all. (Outside the pillars of Heracles the sea is shallow owing to the mud, but calm, for it lies in a hollow.) We see, then, that just as single rivers flow from mountains, so it is with the earth as a whole: the greatest volume of water flows from the higher regions in the north. Their alluvium makes the northern seas shallow, while the outer seas are deeper.
περὶ δὲ τοῦ τὰ πρὸς ἄρκτον εἶναι τῆς γῆς ὑψηλὰ σημεῖόν τι καὶ τὸ πολλοὺς πεισθῆναι τῶν ἀρχαίων μετεωρολόγων τὸν ἥλιον μὴ φέρεσθαι ὑπὸ γῆν ἀλλὰ περὶ τὴν γῆν καὶ τὸν τόπον τοῦτον, ἀφανίζεσθαι δὲ καὶ ποιεῖν νύκτα διὰ τὸ ὑψηλὴν εἶναι πρὸς ἄρκτον τὴν γῆν. 144 Some further evidence of the height of the northern regions of the earth is afforded by the view of many of the ancient meteorologists. They believed that the sun did not pass below the earth, but round its northern part, and that it was the height of this which obscured the sun and caused night.
ὅτι μὲν οὖν οὔτε πηγὰς οἷόν τ' εἶναι τῆς θαλάττης, καὶ διὰ τίν' αἰτίαν οὕτως φαίνεται ῥέουσα, τοιαῦτα καὶ τοσαῦθ' ἡμῖν εἰρήσθω. So much to prove that there cannot be sources of the sea and to explain its observed flow.
Postquam philosophus determinavit de his quae generantur in alto, sive ab exhalatione sicca sive a vapore humido, adiungens etiam de generatione fluviorum, propter similitudinem ad generationem pluviarum, nunc incipit determinare de his quae fiunt in parte inferiori ab exhalatione sicca. Et dividitur in partes duas: 139. After determining concerning things generated on high, from either a dry evaporation or a moist vapor, and after adding a discussion about the generation of rivers on account of its similarity to the generation of rains, the Philosopher now begins to determine concerning things that come to be in the lower region from a dry exhalation. And it is divided into two parts:

in prima determinat de quibusdam principalibus passionibus;

in secunda de quibusdam consequentibus, et hoc in tertio libro, ibi: de residuis autem et cetera.

In the first he determines about certain principal passions, at 140;

In the second about certain things which accompany them ( ).

Prima dividitur in duas: The first is divided into two parts:

in prima determinat de mari, cuius salsedo ex siccitate causatur;

in secunda determinat de ventis et his quae ex eis causantur, ibi: de spiritibus autem dicamus et cetera.

In the first he determines about the sea, whose saltiness is caused by dryness, at 140;

In the second about winds and the things caused by them (L. 7).

Satis autem apparet conveniens ordo quem philosophus observat. Nam post ea quae in suprema parte aeris generantur ab exhalatione sicca, quae stellae cadentes, cometae, lacteus circulus, et similia sunt, in secundo loco determinavit de his quae in inferiori loco generantur ab exhalatione humida, scilicet de pluviis et huiusmodi; et quia eodem modo habent flumina causam generationis in terra, sicut pluviae in aere, post pluvias de fluminibus determinavit; post quae determinat de mari, in quod omnia flumina decurrunt. 140. The order which the Philosopher observes seems quite suitable. For after determining about things generated in the upper region of air from dry exhalation, namely, falling stars, comets, the milky circle and like things, he secondly determined about things generated in the lower region from moist exhalation, namely, rains and so on: and because rivers have a cause of their generation in the earth in the same way as rain in the air, after rains he determined about rivers. After this he determines about the sea, into which all rivers flow.
Circa hoc ergo primo manifestat de quo est intentio. Et dicit quod dicendum est de mari: quae scilicet sit natura ipsius, utrum sit naturalis locus aquae, vel accidentaliter ibi aqua congregetur; et propter quam causam tanta multitudo aquae est salsa; et de prima generatione maris, utrum scilicet habeat principium suae generationis, et quomodo. Concerning this, therefore, he first declares his intention [138] and says that we must speak now of the sea: namely, as to what its nature is, whether it is the natural place of water or is it by accident that water is gathered there; as to what is the cause of such an abundance of water's being salty; and of the primal generation of the sea, i.e., does it have a source of its generation and how?
Secundo ibi: antiqui quidem igitur etc., exequitur propositum. Et circa hoc duo facit: 143. Secondly [139], he pursues his proposition, about which he does two things:

primo ponit opiniones aliorum de mari;

secundo inquirit veritatem, ibi: quod quidem igitur fontes et cetera.

First, he presents the opinions of others about the sea, at 141;

Secondly, he investigates the truth, at 143.

Circa primum duo facit: Concerning the first he does two things:

primo ponit opiniones antiquorum theologorum;

secundo naturalium, ibi: qui autem sapientiores et cetera.

First, he gives the opinions of ancient theologizers, at 141;

Secondly, of the philosophers of nature, at 142.

Circa primum sciendum est quod ante tempora philosophorum, fuerunt quidam qui vocabantur poetae theologi, sicut Orpheus, Hesiodus et Homerus: quia sub tegumento quarundam fabularum, divina hominibus tradiderunt. De his ergo dicit quod posuerunt quod mare habeat fontes proprios ex quibus causatur. Et hoc posuerunt ut terrae et mari non ponerent extranea principia sed propria: putaverunt enim quod terra et aqua sint reverendissima, quasi haec sit magna pars totius universi; et dicebant totum caelum esse propter terram et aquam, et ideo circumdari terram et aquam ab aliis corporibus et ab ipso, ac si haec pars esset honoratissima, et primum principium inter omnia corpora mundi. Regarding the first [139] one must know that before the times of the philosophers there were men called theologizing poets (such as Orpheus, Hesiod and Homer), because under the guise of fables they declared divine things to men. Concerning them, therefore, he says that they posited the sea to have springs of its own from which it is caused. They postulated this so as to avoid attributing to earth and sea extraneous principles not their own: for they believed the earth and sea to be most worthy of reverence, as though they were a great part of the whole universe; and they said that the whole heaven exists for the sake of earth and water and that that is why earth and water are surrounded by other bodies and by the heaven itself, as though this part were most worthy of honor and the first principle among all the bodies of the universe.
Deinde cum dicit: qui autem sapientiores etc., ponit opiniones philosophorum naturalium de mari. Et ponit tres opiniones. Quarum prima est de generatione maris. Et dicit quod illi qui fuerunt sapientiores praedictis poetis sapientia humana (quod dicit quia isti naturales non tractaverunt de divinis, ut illi, sed de naturalibus; quae est sapientia proprie humana, idest conformis humano intellectui): isti ergo dixerunt quod mare habet generationem. Quia a principio totus locus qui est circa terram, erat humidus et plenus aqua, sed est desiccatus a sole per evaporationem humidi; et illud quidem quod evaporavit, secundum eos, causavit aerem et ventos (et ex hoc dicunt causari motum solis et lunae et stellarum); illud autem quod est relictum nondum exsiccatum, est mare. Unde putant quod per continuam exsiccationem semper minoretur, et tandem aliquando totum exsiccabitur, et mare iam non erit. Haec dicitur fuisse opinio Anaxagorae et Diogenis. 142. Then [140] he presents the opinions of the natural philosophers concerning the sea and gives three opinions. The first concerns the generation of the sea and he says that those wiser in "human wisdom" than the aforesaid poets (he says this because the naturalists dealt not with divine things, as did they, but with natural things, which is proper to human wisdom, i.e., conformed to the human intellect), said that the sea has generation. This is because from the beginning the entire region surrounding the earth was wet and full of water, but became dried out by the sun's evaporating the moisture: what evaporated, according to them, caused air and winds (and from this, they say, are caused the movement of the sun and moon and stars); what was left not yet dried up, is the sea. Hence they believe that by a continuous drying-up it is always shrinking, so that finally it will all be dried up and the sea exist no more. This is said to have been the opinion of Anaxagoras and Diogenes.
Secunda opinio est de salsedine maris. Empedocles enim dixit quod terra, calefacta a sole, emittit quendam sudorem, quem credidit esse aquam maris. Et propterea dicit quod mare est salsum, quia etiam sudor animalium invenitur salsus. The second opinion is about the salt of the sea. For Empedocles said that the earth, warmed by the sun, exudes a certain sweat which, he believed, is the water of the sea. For this reason, so he says, the sea is salty, since the sweat of animals also is found to be salty.
Tertia opinio est Anaxagorae etiam de salsedine maris. Qui dixit quod terra per quam transit aqua, vel quae admiscetur aquae, est causa salsedinis maris: sicut enim illud quod colatur per cinerem, fit salsum, sic et aqua maris per admixtionem terrae fit salsa. The third opinion, that of Anaxagoras, also concerns the salt of the sea. He said that the earth through which the water passes, or which is mingled with the water, causes the salt of the sea: for just as something strained through ashes becomes salty, so the water of the sea becomes salty by an admixture of earth.
Deinde cum dicit: quod quidem igitur fontes etc., inquirit veritatem circa praedictas opiniones: 143. Then [141] he searches for the truth regarding these opinions.

et primo circa opinionem poetarum theologizantium;

secundo circa opiniones philosophorum naturalium, ibi: de generatione autem ipsius, si factum est et cetera.

First, about the opinion of the theologizing poets at 143;

Secondly, about the opinions of the philosophers of nature (L. 2).

Circa primum duo facit: About the first he does two things:

primo ostendit quod mare non habet fontes, ut illi dixerunt;

secundo removet quoddam quod videtur suae rationi contrarium, ibi: fluens autem mare videtur et cetera.

First, he shows that the sea has no springs, as they said, at 143;

Secondly, he gives an answer to something seemingly contrary to his own argument, at 145.

Circa primum ponit duas rationes. Quarum prima est, quod aquarum quae sunt circa terram, quaedam sunt fluxibiles, quaedam stationariae. De his quae fluunt, manifestum est quod omnes derivantur ex fontibus. Quod non oportet sic intelligere, quod fontium sit aliquod principium quasi vas continens multitudinem aquae, ex quo flumina deriventur: sed oportet intelligere, ut prius dictum est, quod ex multis partibus, in quibus paulatim generatur, aqua ad unum concurrit, et confluendo primum sibi occurrit ut in tanta multitudine sit. Sed aquarum stationariarum quaedam sunt collectae et sustentatae ab aliquo impediente fluxum earum, vel per artem vel per naturam; quae dicuntur paludosae vel stagnales. Differunt autem haec multitudine et paucitate: nam si fuerint multae aquae sic collectae, dicuntur stagna; si autem paucae, paludes. Quaedam autem aquae stationariae sunt fontanae, idest in ipso suo fonte stant: et omnes istae sunt manufactae, sicut illae quae dicuntur puteales. Omnium enim harum aquarum sic per artem stantium, oportet esse aliquem fontem, qui esset principium fluxus, nisi impediretur per artem. Unde patet quod omnes aquae fontales et fluviales sponte fluunt secundum impetum naturae, vel indigent operatione artis ad hoc quod stent. Concerning the first [141] he presents two arguments. The first is that among the waters surrounding the earth, some can flow and some are stationary. Of those that flow it is plain that all are derived from springs. But this does not mean that the springs have as their source, as it were, a container holding a vast store of water, from which rivers are derived: it means, as already stated, that from the many places where it is formed little by little [drop by drop], the water comes together, and that it is by such confluence that it for the first time comes to be in so great a quantity. But with regard to stationary waters, some are collected and held in one place by something artificial or natural that obstructs the flow, and are called marshes or ponds. These differ by reason of largeness or smallness: for if a large store of water has been thus collected, it is called a pond; if a little, a marsh. Now, some stationary waters are "fountainous," i.e., they subsist in their own source; all such are man-made, for example, wells. For all such waters thus stationary through art must have a spring, which would make them flow unless they were artificially prevented. Hence it is plain that all water from fountains and rivers flows of itself according to the inclination of nature, or, if it is to be stationary, must be made so artificially.
Quibus determinatis, patet quod aqua maris non est de fontibus, quia in nullo duorum dictorum generum continetur: quia nec fluit, ut fluvialis, nec potest dici quod sit manufacta, ut putealis. Omnes autem aquae quae sunt ex fontibus, vel fluunt, vel stant per artem: nisi forte aliquae sint parvae aquae quae sponte stent non per artem, sicut contingit cum aqua fluens invenit aliquam concavitatem aut aliquod obstaculum. Sed hoc non potest esse in magna quantitate: quia dum multiplicatur aqua fluens, oportet quod vel supergrediatur obstaculum et iterum fluat, vel submergatur in terra, sicut in multis locis accidit, ut supra dictum est. Unde non potest dici quod tanta aqua sicut aqua maris, possit spontanee stare, si sit ex fontibus. Relinquitur ergo quod mare non habeat fontes. In the light of the foregoing it is plain that the water of the sea does not come from springs, because it falls within neither of the groups mentioned: it does not flow, as river water does, and we cannot say that it is man-made, as a well is. But all waters that come from springs either flow or are stationary by art — unless you include small bodies of water that stand of themselves and not artificially, as when flowing water finds its way into a hollow or meets an obstacle. But such water cannot exist in large amounts: because when the flow water increases, it must either run over the obstacle and start to flow again, or be submerged within the earth, as, we have said, happens in many places. Hence it cannot be said that such a quantity of water as the water of the sea could be standing of itself, if it arose from springs. The conclusion, therefore, is that the sea does not have springs.
Secundam rationem ponit ibi: adhuc autem quoniam plura sunt et cetera. Et dicit quod multa maria sunt quae in nullo loco adinvicem commiscentur. Nam mare rubrum coniungitur quidem secundum modicum ad mare Oceanum, quod est extra columnas Herculis; a quo mari omnino separata sunt mare Hyrcanum et Caspium (quod est mare Ponticum); et habitantur undique per circuitum, ita quod non laterent fontes illius maris, si illud mare fontes haberet. Non ergo verum est quod maris sint aliqui fontes. 144. He gives the second argument [142] and says that there are many seas that have no communication with any other. For the Red Sea joins but slightly with the Ocean Sea beyond the columns of Hercules: from which sea the Hyrcanian and Caspian (which is the sea of Pontus) are far removed. If they had springs, the people who live along all the sides of the sea would not have failed to discover them. It is therefore not true that springs of the sea exist.
Deinde cum dicit: fluens autem mare videtur etc., quia in quibusdam maribus apparet communis fluxus, ne credatur mare esse fluxibile tanquam ex fontibus procedens, cuius contrarium in prima ratione supposuerat, assignat causam fluxus qui videtur in mari. Et circa hoc tria facit: 145. Then [143] because a common flow is apparent in some seas, lest it be supposed that the sea can flow, as if proceeding from springs, the contrary of which he had supposed in the first argument, he assigns the cause of the flow seen in the sea. About this he does three things:

primo ostendit quare aliquod mare fluat;

secundo manifestat quoddam quod supponit, per signum, ibi: de eo autem etc.;

tertio recapitulat, ibi: quod quidem igitur et cetera.

First, he shows why some sea flows, at 145;

Secondly, he manifests what he supposed with a sign, at 146;

Thirdly, he summarizes at end of 146.

Assignat autem fluxus maris tres causas. Quarum prima est, quod mare fluit propter eius angustiam, ubi ex magno pelago restringitur in modicum spatium, propter hoc quod coarctatur ab adiacente terra. Aqua autem maris saepe movetur huc et illuc, et maxime secundum consequentiam ad motum lunae, quae secundum naturam propriam habet commovere humidum: haec autem aquae commotio in magno mari et amplo est immanifesta; sed ubi obtinent parvum locum propter angustiam terrae, magis apparet. \ Now he assigns three causes of the sea's flowing [143]. The first is that the sea flows because of its narrowness, where, from being a vast flood, it is confined into a small place because of being narrowed by adjacent land. Now the water of the sea is often moved back and forth, especially as a consequence of the movement of the moon, whose proper nature it is to agitate the moist: but this commotion of water in a large open sea goes unnoticed, but where it occurs in an area rendered small by the narrowness of the land it becomes more noticeable.
Secunda causa est, quod illud mare quod continetur infra Heracleas columnas, et non continuatur alicui, sicut de mari Pontico iam dictum est: istud, inquam, fluit propter multitudinem fluviorum. Et propter eandem causam unum mare decurrit in aliud: nam Maeotis fluit in mare Ponticum, Ponticum fluit in Aegeum. In aliis autem maribus minus hoc videtur: sed in praedictis maribus hoc accidit propter multitudinem fluviorum, quia in praedicta maria multa flumina intrant. The second cause is that the sea which is contained within the columns of Hercules and does not communicate with any other sea (as was already said of the Sea of Pontus), that sea, I say, flows on account of the large number of rivers. And, for the same reason, one sea flows into another: for Maeotis flows into the Sea of Pontus and the Pontus into the Aegean. In other seas this is not so evident; but in the ones mentioned this happens on account of the number of rivers, for many rivers flow into them.
Tertia ratio fluxus est propter hoc quod mare occupat multum de terra secundum proportionem quantitatis aquae, et unum est minus profundum quam aliud: illud autem quod est minus profundum, semper decurrit ad profundius. Unde illud mare semper videtur profundius, ad quod aliud decurrit, sicut Ponticum est profundius Maeotide, et Pontico mare Aegeum, et Aegeo Siculum; Sardicum autem et Tyrrhenum sunt profundissima. Sed mare quod est extra columnas, non est profundum: quod apparet ex luto apparente in aqua quae fluit ex ipso; et huius signum est quod sunt sine vento, ac si existant in aliqua concavitate. Sicut igitur particulariter fluvii videntur fluentes ex altioribus locis ad demissiora, sic in mari fluxus fit ex altioribus locis terrae, quae sunt ad Septentrionem: ut sic maria Septentrionalia, quae emittunt aquam, non sint ita profunda sicut maria meridionalia, quae recipiunt. The third reason for the flow is that a sea covers a great deal of earth, in keeping with the quantity of the water, and one sea is not as deep as another; but the one that is not so deep always flows to the deeper one. Hence that sea to which another flows is always seen to be deeper: as, for example, the Pontus is deeper than Maeotis, the Aegean than the Pontus, and the sea of Sicily deeper than the Aegean; but the..Sofian and the Etruscan are the deepest of all. The sea beyond the Columns, however, is not deep, as is evident from the mud in the water flowing out of it. An indication of this is that it is calm, as though it were in a hollow. Therefore, just as individual rivers are seen flowing from higher to lower places, so in the sea, the flow is from the loftier places of the earth, which are in the north: consequently, the northern seas, from which water flows, are not as deep as those in the south which receive it.
Deinde cum dicit: de eo autem etc., manifestat per signum quoddam quod dixerat, scilicet quod terra ex parte Septentrionis sit altior. Et huius signum accipit ex hoc quod quidam antiquorum crediderunt quod sol non iret sub terra, sed solum circa terram, et dispareret de nocte propter altitudinem Septentrionalis partis occultantis. Deinde cum dicit: quod quidem igitur etc., recapitulat quod dixerat: et est planum in littera. 146. Then [144] through a certain sign he manifests what he had said, namely, that the earth is higher toward the north. He takes as an indication of this the fact that some of the ancients believed that the sun did not go below the earth but only around it and that it became invisible at night because the northern heights obscured it. — Then [145] he summarizes what he had said — and it is plain in the text.

Lecture 2
The sea is shown to be the natural place of all water
Chapter 2
(354b.) περὶ δὲ τῆς γενέσεως αὐτῆς, εἰ γέγονε, καὶ τοῦ χυμοῦ, τίς ἡ αἰτία τῆς ἁλμυρότητος καὶ πικρότητος, λεκτέον. 146 We must now discuss the origin of the sea, if it has an origin, and the cause of its salt and bitter taste.
ἡ μὲν οὖν αἰτία ἡ ποιήσασα τοὺς πρότερον οἴεσθαι τὴν θάλατταν ἀρχὴν εἶναι καὶ σῶμα τοῦ παντὸς ὕδατος ἥδ' ἐστίν δόξειε γὰρ ἂν εὔλογον εἶναι, καθάπερ καὶ τῶν ἄλλων στοιχείων ἐστὶν ἠθροισμένος ὄγκος καὶ ἀρχὴ διὰ τὸ πλῆθος, ὅθεν μεταβάλλει τε μεριζόμενον καὶ μείγνυται τοῖς ἄλλοις—οἷον πυρὸς μὲν ἐν τοῖς ἄνω τόποις, ἀέρος δὲ πλῆθος τὸ μετὰ τὸν τοῦ πυρὸς τόπον, γῆς δὲ σῶμα περὶ ὃ ταῦτα πάντα κεῖται φανερῶς ὥστε δῆλον ὅτι κατὰ τὸν αὐτὸν λόγον καὶ περὶ ὕδατος ἀνάγκη ζητεῖν. τοιοῦτον δ' οὐδὲν ἄλλο φαίνεται σῶμα κείμενον ἀθρόον, ὥσπερ καὶ τῶν ἄλλων στοιχείων, πλὴν τὸ τῆς θαλάττης μέγεθος τὸ γὰρ τῶν ποταμῶν οὔτ' ἀθρόον οὔτε στάσιμον, ἀλλ' ὡς γιγνόμενον ἀεὶ φαίνεται καθ' ἡμέραν. 147 What made earlier writers consider the sea to be the original and main body of water is this. It seems reasonable to suppose that to be the case on the analogy of the other elements. Each of them has a main bulk which by reason of its mass is the origin of that element, and any parts which change and mix with the other elements come from it. Thus the main body of fire is in the upper region; that of air occupies the place next inside the region of fire; while the mass of the earth is that round which the rest of the elements are seen to lie. So we must clearly look for something analogous in the case of water. But here we can find no such single mass, as in the case of the other elements, except the sea. River water is not a unity, nor is it stable, but is seen to be in a continuous process of becoming from day to day. It was this difficulty which made people regard the sea as the origin and source of moisture and of all water. And so we find it maintained that rivers not only flow into the sea but originate from it, the salt water becoming sweet by filtration.
ἐκ ταύτης δὴ τῆς ἀπορίας καὶ ἀρχὴ τῶν ὑγρῶν ἔδοξεν εἶναι καὶ τοῦ παντὸς ὕδατος ἡ θάλαττα. 148 But this view involves another difficulty. If this body of water is the origin and source of all water, why is it salt and not sweet?
διὸ καὶ τοὺς ποταμοὺς οὐ μόνον εἰς ταύτην ἀλλὰ καὶ ἐκ ταύτης φασί τινες ῥεῖν διηθούμενον γὰρ γίγνεσθαι τὸ ἁλμυρὸν πότιμον. ἀντίκειται δὲ ἑτέρα πρὸς ταύτην τὴν δόξαν ἀπορία, τί δή ποτ' οὐκ ἔστιν τὸ συνεστὸς ὕδωρ τοῦτο πότιμον, εἴπερ ἀρχὴ τοῦ παντὸς ὕδατος, ἀλλ' ἁλμυρόν. τὸ δ' αἴτιον ἅμα ταύτης τε τῆς ἀπορίας λύσις ἔσται, καὶ περὶ θαλάττης τὴν πρώτην λαβεῖν ὑπόληψιν ἀναγκαῖον ὀρθῶς. τοῦ γὰρ ὕδατος περὶ τὴν γῆν περιτεταμένου, καθάπερ περὶ τοῦτο ἡ τοῦ ἀέρος σφαῖρα καὶ περὶ ταύτην ἡ λεγομένη πυρός (τοῦτο γάρ ἐστι πάντων ἔσχατον, εἴθ' ὡς οἱ πλεῖστοι λέγουσιν εἴθ' ὡς ἡμεῖς), φερομένου δὲ τοῦ ἡλίου τοῦτον τὸν τρόπον, καὶ διὰ ταῦτα τῆς μεταβολῆς καὶ γενέσεώς τε καὶ φθορᾶς οὔσης, τὸ μὲν λεπτότατον καὶ γλυκύτατον ἀνάγεται καθ' ἑκάστην ἡμέραν καὶ φέρεται διακρινόμενον καὶ ἀτμίζον εἰς τὸν ἄνω τόπον, ἐκεῖ δὲ πάλιν συστὰν διὰ τὴν ψύξιν καταφέρεται πάλιν πρὸς τὴν γῆν. 149 The reason for this, besides answering this question, will ensure our having a right first conception of the nature of the sea. The earth is surrounded by water, just as that is by the sphere of air, and that again by the sphere called that of fire (which is the outermost both on the common view and on ours). Now the sun, moving as it does, sets up processes of change and becoming and decay, and by its agency the finest and sweetest water is every day carried up and is dissolved into vapour and rises to the upper region, where it is condensed again by the cold and so returns to the earth. This, as we have said before, is the regular course of nature.
καὶ τοῦτ' ἀεὶ βούλεται ποιεῖν ἡ φύσις οὕτως, καθάπερ εἴρηται πρότερον. διὸ καὶ γελοῖοι πάντες ὅσοι τῶν πρότερον ὑπέλαβον τὸν ἥλιον τρέφεσθαι τῷ ὑγρῷ καὶ διὰ τοῦτ' ἔνιοί γέ (355a.) φασιν καὶ ποιεῖσθαι τὰς τροπὰς αὐτόν οὐ γὰρ αἰεὶ τοὺς αὐτοὺς δύνασθαι τόπους παρασκευάζειν αὐτῷ τὴν τροφήν ἀναγκαῖον δ' εἶναι τοῦτο συμβαίνειν περὶ αὐτὸν ἢ φθείρεσθαι καὶ γὰρ τὸ φανερὸν πῦρ, ἕως ἂν ἔχῃ τροφήν, μέχρι τούτου ζῆν, τὸ δ' ὑγρὸν τῷ πυρὶ τροφὴν εἶναι μόνον, 150 Hence all my predecessors who supposed that the sun was nourished by moisture are absurdly mistaken. Some go on to say that the solstices are due to this, the reason being that the same places cannot always supply the sun with nourishment and that without it he must perish. For the fire we are familiar with lives as long as it is fed, and the only food for fire is moisture.
—ὥσπερ ἀφικνούμενον μέχρι πρὸς τὸν ἥλιον τὸ ἀναγόμενον τοῦ ὑγροῦ, 151 As if the moisture that is raised could reach the sun!
ἢ τὴν ἄνοδον τοιαύτην οὖσαν οἵανπερ τῇ γιγνομένῃ φλογί, δι' ἧς τὸ εἰκὸς λαβόντες οὕτω καὶ περὶ τοῦ ἡλίου ὑπέλαβον. τὸ δ' οὐκ ἔστιν ὅμοιον ἡ μὲν γὰρ φλὸξ διὰ συνεχοῦς ὑγροῦ καὶ ξηροῦ μεταβαλλόντων γίγνεται καὶ οὐ τρέφεται (οὐ γὰρ ἡ αὐτὴ οὖσα διαμένει οὐδένα χρόνον ὡς εἰπεῖν), περὶ δὲ τὸν ἥλιον ἀδύνατον τοῦτο συμβαίνειν, ἐπεὶ τρεφομένου γε τὸν αὐτὸν τρόπον, ὥσπερ ἐκεῖνοί φασιν, δῆλον ὅτι καὶ ὁ ἥλιος οὐ μόνον καθάπερ Ἡράκλειτός φησιν, νέος ἐφ' ἡμέρῃ ἐστίν, ἀλλ' ἀεὶ νέος συνεχῶς. 152 or this ascent were really like that performed by flame as it comes into being, and to which they supposed the case of the sun to be analogous! Really there is no similarity. A flame is a process of becoming, involving a constant interchange of moist and dry. It cannot be said to be nourished since it scarcely persists as one and the same for a moment. This cannot be true of the sun; for if it were nourished like that, as they say it is, we should obviously not only have a new sun every day, as Heraclitus says, but a new sun every moment.
ἔτι δ' ἡ ὑπὸ τοῦ ἡλίου ἀναγωγὴ τοῦ ὑγροῦ ὁμοία τοῖς θερμαινομένοις ἐστὶν ὕδασιν ὑπὸ πυρός εἰ οὖν μηδὲ τὸ ὑποκαόμενον τρέφεται πῦρ, οὐδὲ τὸν ἥλιον εἰκὸς ἦν ὑπολαβεῖν, οὐδ' εἰ πᾶν θερμαίνων ἐξατμίσειεν τὸ ὕδωρ. 153 Again, when the sun causes the moisture to rise, this is like fire heating water. So, as the fire is not fed by the water above it, it is absurd to suppose that the sun feeds on that moisture, even if its heat made all the water in the world evaporate.
ἄτοπον δὲ καὶ τὸ μόνον φροντίσαι τοῦ ἡλίου, τῶν δ' ἄλλων ἄστρων αὐτοὺς παριδεῖν τὴν σωτηρίαν, τοσούτων καὶ τὸ πλῆθος καὶ τὸ μέγεθος ὄντων. 154 Again, it is absurd, considering the number and size of the stars, that these thinkers should consider the sun only and overlook the question how the rest of the heavenly bodies subsist.
τὸ δ' αὐτὸ συμβαίνει καὶ τούτοις ἄλογον καὶ τοῖς φάσκουσι τὸ πρῶτον ὑγρᾶς οὔσης καὶ τῆς γῆς, καὶ τοῦ κόσμου τοῦ περὶ τὴν γῆν ὑπὸ τοῦ ἡλίου θερμαινομένου, ἀέρα γενέσθαι καὶ τὸν ὅλον οὐρανὸν αὐξηθῆναι, καὶ τοῦτον πνεύματά τε παρέχεσθαι καὶ τὰς τροπὰς αὐτοῦ ποιεῖν φανερῶς γὰρ ἀεὶ τὸ ἀναχθὲν ὁρῶμεν καταβαῖνον πάλιν ὕδωρ κἂν μὴ κατ' ἐνιαυτὸν ἀποδιδῷ καὶ καθ' ἑκάστην ὁμοίως χώραν, ἀλλ' ἔν γέ τισιν τεταγμένοις χρόνοις ἀποδίδωσι πᾶν τὸ ληφθέν, ὡς οὔτε τρεφομένων τῶν ἄνωθεν, οὔτε τοῦ μὲν μένοντος ἀέρος ἤδη μετὰ τὴν γένεσιν, τοῦ δὲ γιγνομένου καὶ φθειρομένου πάλιν εἰς ὕδωρ, ἀλλ' ὁμοίως ἅπαντος διαλυομένου καὶ συνισταμένου πάλιν εἰς ὕδωρ. 155 Again, they are met by the same difficulty as those who say that at first the earth itself was moist and the world round the earth was warmed by the sun, and so air was generated and the whole firmament grew, and the air caused winds and solstices. The objection is that we always plainly see the water that has been carried up coming down again. Even if the same amount does not come back in a year or in a given country, yet in a certain period all that has been carried up is returned. This implies that the celestial bodies do not feed on it, and that we cannot distinguish between some air which preserves its character once it is generated and some other which is generated but becomes water again and so perishes; on the contrary, all the moisture alike is dissolved and all of it condensed back into water.
τὸ μὲν οὖν πότιμον καὶ γλυκὺ διὰ κουφότητα πᾶν ἀνάγεται, τὸ δ' ἁλμυρὸν ὑπομένει διὰ βάρος οὐκ ἐν τῷ αὐτοῦ οἰκείῳ τόπῳ τοῦτο γὰρ οἰητέον ἀπορηθῆναί τε προσηκόντως (ἄλογον γὰρ εἰ μή (355b.) τίς ἐστιν τόπος ὕδατος ὥσπερ καὶ τῶν ἄλλων στοιχείων) καὶ ταύτην εἶναι λύσιν ὃν γὰρ ὁρῶμεν κατέχουσαν τόπον τὴν θάλατταν, οὗτος οὐκ ἔστιν θαλάττης ἀλλὰ μᾶλλον ὕδατος. φαίνεται δὲ θαλάττης, ὅτι τὸ μὲν ἁλμυρὸν ὑπομένει διὰ τὸ βάρος, τὸ δὲ γλυκὺ καὶ πότιμον ἀνάγεται διὰ τὴν κουφότητα, καθάπερ ἐν τοῖς τῶν ζῴων σώμασιν. καὶ γὰρ ἐν τούτοις τῆς τροφῆς εἰσελθούσης γλυκείας ἡ τῆς ὑγρᾶς τροφῆς ὑπόστασις καὶ τὸ περίττωμα φαίνεται πικρὸν ὂν καὶ ἁλμυρόν τὸ γὰρ γλυκὺ καὶ πότιμον ὑπὸ τῆς ἐμφύτου θερμότητος ἑλκυσθὲν εἰς τὰς σάρκας καὶ τὴν ἄλλην σύνταξιν ἦλθεν τῶν μερῶν, ὡς ἕκαστον πέφυκεν. ὥσπερ οὖν κἀκεῖ ἄτοπον εἴ τις τῆς ποτίμου τροφῆς μὴ νομίζοι τόπον εἶναι τὴν κοιλίαν, ὅτι ταχέως ἀφανίζεται, ἀλλὰ τοῦ περιττώματος, ὅτι τοῦθ' ὁρᾷ ὑπομένον, οὐκ ἂν ὑπολαμβάνοι καλῶς. ὁμοίως δὲ καὶ ἐν τούτοις ἔστιν γάρ, ὥσπερ λέγομεν, οὗτος ὁ τόπος ὕδατος διὸ καὶ οἱ ποταμοὶ ῥέουσιν εἰς αὐτὸν ἅπαντες καὶ πᾶν τὸ γιγνόμενον ὕδωρ εἴς τε γὰρ τὸ κοιλότατον ἡ ῥύσις, καὶ ἡ θάλαττα τὸν τοιοῦτον ἐπέχει τῆς γῆς τόπον ἀλλὰ τὸ μὲν ἀναφέρεται ταχὺ διὰ τὸν ἥλιον ἅπαν, τὸ δ' ὑπολείπεται διὰ τὴν εἰρημένην αἰτίαν. 156 The drinkable, sweet water, then, is light and is all of it drawn up: the salt water is heavy and remains behind, but not in its natural place. For this is a question which has been sufficiently discussed (I mean about the natural place that water, like the other elements, must in reason have), and the answer is this. The place which we see the sea filling is not its natural place but that of water. It seems to belong to the sea because the weight of the salt water makes it remain there, while the sweet, drinkable water which is light is carried up. The same thing happens in animal bodies. Here, too, the food when it enters the body is sweet, yet the residuum and dregs of liquid food are found to be bitter and salt. This is because the sweet and drinkable part of it has been drawn away by the natural animal heat and has passed into the flesh and the other parts of the body according to their several natures. Now just as here it would be wrong for any one to refuse to call the belly the place of liquid food because that disappears from it soon, and to call it the place of the residuum because this is seen to remain, so in the case of our present subject. This place, we say, is the place of water. Hence all rivers and all the water that is generated flow into it: for water flows into the deepest place, and the deepest part of the earth is filled by the sea. Only all the light and sweet part of it is quickly carried off by the sun, while the rest remains for the reason we have explained.
Hic incipit inquirere veritatem circa opiniones quas habuerunt antiqui naturales de mari. 147. Here he begins to search into the truth about the opinions which the ancient natural philosophers held about the sea.

Et primo ostendit de quo est intentio: dicens quod est de generatione maris, si est factum; et de sapore eius, quae sit causa salsedinis et amaritudinis ipsius.

Secundo ibi: causa quidem igitur etc., exequitur propositum.

First, he shows what his intention is about [126] and says that it is about the generation of the sea: if it was made, and of its savor — as to what is the cause of its salty and bitter taste;

Secondly, he pursues the proposition, at 148.

Et dividitur in partes tres: This is divided into three parts:

in prima determinat de natura maris, utrum scilicet sit naturalis locus aquae;

in secunda determinat de generatione eius, utrum scilicet sit factum vel non, ibi, de salsedine autem etc.;

in tertia determinat de sapore maris, quare scilicet sit salsum, ibi: de salsedine autem his quidem et cetera.

In the first he determines about the nature of the sea: whether it is the natural place of water, at 148;

In the second about its generation: whether or not it was made (L. 4);

In the third about its savor: why it is salty (L. 5).

Prima autem pars dividitur in partes duas: The first part is divided into two parts:

in prima ostendit opinionem antiquorum de natura maris;

in secunda obiicit contra eam, ibi: opponitur autem et cetera.

In the first he shows the opinion of the ancients about the nature of the sea, at 148;

In the second he objects against it, at 149.

Dicit ergo primo quod antiqui putaverunt quod mare sit principium omnis aquae, et quod sit substantia et corpus totius aquae, quasi mare sit naturalis locus aquae. Et causa inducens eos ad hoc fuit, quod videbatur rationabile esse quod, sicut omnium aliorum elementorum magnitudo est congregata in unum locum, et est unum principium unde derivatur partialiter elementum et commiscetur aliis elementis, propter multitudinem substantiae elementaris in illo loco existentis, ita est in aqua. Videmus enim quod multitudo ignis est in superiori loco huius inferioris mundi, qui est naturalis locus eius; et similiter multitudo aeris est sub loco ignis, quasi in proprio loco congregata; et manifestum est quod corpus terrae est in medio, circa quod omnia alia corpora sunt ordinata. Unde manifestum est quod necesse est etiam, secundum eandem rationem, esse aliquem locum ubi sit congregata multitudo aquae, quasi in loco proprio et naturali. 148. He says therefore first [147] that the ancients thought the sea to be the source of all water, and that it is the substance and body of the totality of water, as though the sea were the natural place of water. And the cause which led them to this was that it seemed reasonable that, just as the main bulk of all other elements is gathered into one place, and there is one source from which are derived those portions of that element which mingle with other elements, due to the size of the elemental substance, so too with water. For we observe that the main body of fire exists in the upper region of this lower world, which is its natural place; likewise, the main body of air exists under the region of fire, as though gathered together in its appropriate place; and it is plain that the body of earth is in the center, around which all other bodies are ordered. Hence it is plain that according to the same reasoning, it is also necessary that there be a place where the main bulk of water be congregated, as in its proper and natural place.
Huiusmodi autem non potest esse aliud quam mare: quia aquae fluviorum non sunt omnes simul, cum tamen oporteat unius elementi esse unum locum continuum. Iterum aqua fluviorum non est stabilis, sed fluens, cum tamen oporteat omne elementum stare in proprio loco: fluit autem fluviorum aqua, utpote quae videtur semper generari, et non quiescere in eodem loco. Such a place can be naught but the sea: because the waters of streams are not all of them together, whereas for one element there must be one continuous place. Further, the water of rivers is not stationary but flowing, whereas every element must be stable in its proper place — for the water of rivers flows so as to seem to be forever coming into existence and not remaining in the same place.
Propter hanc igitur dubitationem, putaverunt quod mare esset principium omnis aquae et omnium humidorum. Et propter hoc putaverunt quod omnia flumina non solum intrant in mare, sed etiam fluunt a mari: quia locus naturalis alicuius elementi videtur esse principium et terminus motus omnium illorum quae sunt de natura illa, quia omnia naturaliter tendunt ad locum proprium. Et secundum antiquos erat etiam principium: quia ponebant quod elementa erant ingenerabilia et incorruptibilia, unde aqua non generabatur de novo; et sic oportebat quod, ubicumque aqua extra locum proprium inveniretur, quod influeret a naturali loco aquae. On account of this problem they thought that the sea was the source of all water and of all moist things. On which account they thought that all rivers not only flow into the sea, but from it as well — since the natural place of an element seems to be the source and terminus of the movements of all things that possess its nature, for all things naturally tend to their own place. And according to the ancients it was also the source since they held the elements to be ungenerated and incorruptible — hence water was not newly generated. Thus, wherever water might be found outside its proper place, it would have had to have flowed from the natural place of water.
Et quia posset aliquis obiicere quod mare est salsum, et aqua fluviorum est dulcis, et sic non videtur fluens a mari; ad hanc obiectionem excludendam, subditur quod illud quod est salsum, quando colatur, fit dulce; et sic aqua maris, quando colatur per terram, efficitur potabilis in fluviis. And because one could object that the sea is salty, whereas the water of rivers is sweet, and consequently does not seem to flow from the sea, they add, to dismiss this objection, that when something salty is filtered, it becomes sweet; and so sea water, when filtered through earth, becomes drinkable in rivers.
Deinde cum dicit: opponitur autem etc., movet quasdam dubitationes circa praedeterminata: 149. Then [148] he raises certain doubts about these previous determinings:

et primo unam contra hoc quod mare est locus naturalis aquae;

secundo contra hoc quod dictum est quod mare est terminus aquarum currentium, ibi: quaerere autem antiquam et cetera.

First, a doubt against the sea's being the natural place of water, at 149;

Secondly, against the sea's being the terminus of running waters (L. 3).

Circa primum duo facit. About the first he does two things:
Primo movet dubitationem: quae talis est. Si mare est principium omnis aquae, quasi naturalis locus aquae existens, quare aqua maris non est dulcis et potabilis, sed salsa? Omne enim elementum in primo loco videtur esse intransmutatum, et naturaliter se habens: salsedo autem non est naturalis proprietas aquae, sed ex aliqua transmutatione ei accidit. First, he raises this doubt [148], which is as follows: If the sea is the source of all water as though it were the natural place of water, why is sea water not sweet and drinkable but salty? For every element in its primal place is seen to be untransformed and in its natural state — while saltiness is not a natural property of water but is due to some transmutations,
Secundo ibi: causa autem simul etc., solvit praedictam dubitationem. Et circa hoc tria facit: 150. Secondly [149], he solves this doubt. In connection with this, he does three things:

primo praemittit quoddam, resumens ex praedeterminatis, quod est necessarium ad solutionem;

secundo ex hoc quod propositum est, excludit quandam falsam opinionem, ibi: propter quod et deridendi etc.;

tertio solvit dubitationem, ibi: potabile quidem igitur et cetera.

First, from matters already determined he takes something necessary for the solution;

Secondly, from what was proposed he dismisses a certain false opinion, at 151;

Thirdly, he settles the doubt, at 153.

Dicit ergo primo quod assignando causam praedictae dubitationis, non solum solvetur haec dubitatio, sed necessarium erit per hoc accipere rectam opinionem de mari. Resumit ergo quod aqua est ordinata circa terram, sicut sphaera ignis super aerem, et sphaera aeris super aquam. Ignis enim est supremum elementorum, sive ignis existimetur esse corpus caeleste, ut plurimi dicunt, sive sit quoddam corpus ordinatum sub caelesti corpore, sicut ipse supra dixit. Cum igitur ex solis motu causetur generatio et corruptio, et omnes permutationes in istis inferioribus, oportet quod illud quod est subtilissimum et dulcissimum in aqua rarefacta, evaporans continue feratur in superiorem locum; et ibi iterum condensatum ex virtute frigoris, feratur deorsum in terram. Et hoc semper fit secundum naturam, ut prius dictum est. He says therefore first [149], that in assigning the cause of this doubt, not only will it be solved, but it will be necessary through it to obtain the correct opinion about the sea. He recalls, therefore, that water is positioned around the earth, as the sphere of fire above the air, and as the sphere of air above the water. For fire is the highest of the elements, whether fire be taken as the heavenly body, as very many hold, or as a body situated under the heavenly body, as he held above. Now, since generation and corruption, and all changes affecting lower bodies, are caused by the movement of the sun, what is finest and sweetest in rarified water must be, as evaporated continually, brought to an upper region, where it is again condensed by the power of the cold and carried downward to earth. And this is always happening by nature, as already stated.
Deinde cum dicit: propter quod et deridendi etc., excludit quandam falsam opinionem per praemissa. Et primo ponit opinionem. Et dicit quod per praedicta patet quod deridendi sunt antiqui, qui dixerunt quod sol cibaretur humido aquoso, et ob hanc causam circumiret, quia idem locus non potest semper praebere huiusmodi alimentum; quod est necessarium ipsum habere, aut, nisi ipsum haberet, corrumperetur. Putabant enim quod sol esset naturae igneae: manifestum est autem quod quandiu ignis habuerit nutrimentum, tandiu durat; solum autem humidum est nutrimentum ignis. Unde, consumpto totaliter humido, extinguitur ignis. 151. Then [150] he uses this to dismiss a false opinion. First, he cites the opinion and says that from the foregoing it is plain that those ancients should be laughed at who said that the sun was fed by the watery moisture, and that it moved about because the same place cannot always offer this nourishment which it must have or be destroyed by not having it. For they thought that the sun was of a fiery nature. Now it is plain that fire lasts only so long as it is fed, and that the moist alone is its food. Consequently, when the moisture is totally consumed, the fire dies out.
Secundo ibi: tanquam pertingat etc., improbat praedictam positionem quinque rationibus. Quarum prima est, quod vapor qui sursum elevatur, non ascendit usque ad locum solis, ut exinde possit cibari. Et hoc satis ex praedictis potest esse manifestum. 152. Secondly [151], he assails this opinion with five reasons. The first is that vapor which is lifted upward does not ascend as far as the sun's place, so as to be its food. This is plain enough from what has been already said.
Secundam rationem ponit ibi: aut ascensus et cetera. Quae est quod ponentes hoc quod dictum est, videntur existimare quod talis sit ascensus vaporis ad solem, qualis est ascensus fumi ad flammam; ex qua acceperunt signum ad sic opinandum de sole. Sed non est simile. Quia flamma non semper manet eadem, sed continue fit nova, per hoc quod materia alia et alia continue inflammatur; quae quidem prius est humida, apta inflammationi, et per ignem totaliter desiccatur, et desinit inflammari, et succedit alia. Et sic patet quod flamma non nutritur: quia quod nutritur oportet manere idem, ut patet in animalibus et plantis; sed flamma quasi nullo tempore permanet, ut dictum est. Sed hoc non potest accidere circa solem: quia si sic nutriretur secundum quod ipsi dicunt, continue innovaretur, et non solum semel in die, sicut posuit Heraclitus. Then [152] he presents the second reason which is that those who held that opinion seemed to think that the rise of vapor to the sun is as the rise of smoke to a flame: from the latter they took their basis for thinking as they do about the sun. But there is no similarity. For a flame never remains the same individual but is continually becoming a new thing by the fact that other and other material is continually enkindled: the matter, originally moist and suitable for combustion, is completely dried up by the fire and ceases to be inflamed, and is then succeeded by other matter. And so it is plain that a flame is not fed, because what is fed must retain its identity, as is plain in animals and plants, whereas a flame persists as though for no time at all, as has been said. Now such a state of affairs cannot be true of the sun: for if it were fed in the way they claim', it would be re-born continually and not just once every day, as Heraclitus postulated.
Tertiam rationem ponit ibi: adhuc autem et cetera. Et dicit quod elevatio vaporis humidi ad solem, similis est calefactioni aquarum in ollis igne supposito. Ignis autem ardens sub olla non nutritur ab aqua evaporante. Unde nec etiam sol, si faciat evaporare tantam aquam. He presents the third reason [153] and says that the rising of moist vapor to the sun is akin to the boiling of water in pans over a fire. But the fire burning under the pan is not fed by the evaporating water. Therefore, neither is the sun, if it should cause so much water to evaporate.
Quartam rationem ponit ibi: inconveniens autem et cetera. Et dicit quod inconveniens fuit quod attribuerent tantum soli nutrimentum, et non aliis stellis, ad eorum salutem, cum tamen ponantur ab eis igneae naturae. Quae quidem astra sunt tot et tam magna, quod tota aqua non sufficeret ad nutrimentum eorum. He presents the fourth reason [153] and says that it is inconsistent to postulate food for the sun only and not for the other stars, if they are to remain healthy, since they too are assumed by them to be of a fiery nature. Indeed, these stars are so many and so large that the totality of water would not be enough to feed them.
Quintam rationem ponit ibi: idem autem accidit et cetera. Et dicit hanc rationem esse communiter et contra istam opinionem, et contra illos qui dixerunt quod a principio tota terra erat cooperta aquis, et postea, aqua vaporante ex calore solis, esse factum aerem; et sic totum caelum est augmentatum, per hoc quod aer, cum sit rarior, plus occupat de loco quam aqua ex qua generatur; et hoc quod sic est resolutum ab aquis, causat ventos et motum caeli. Utraque igitur harum opinionum destruitur per hoc quod manifeste videmus illud quod elevatur sursum ab aquis, iterum redire ad terram; et si non per eundem locum et similiter per omnes regiones (quia aliquando, et in quibusdam regionibus, plus evaporat quam pluat ibi), sed tamen in aliquibus locis, per aliquam ordinationem temporis, omne quod sursum elevatur, redit iterum ad terram. Et sic patet quod neque superiora corpora aluntur ex vaporibus; neque aliqua pars vaporis remanet aer, et alia iterum redit in aquam. He presents the fifth reason [155] and says that this argument is both against this position and against those who held that in the beginning the entire earth was covered with water, but that later, as the water was evaporated by the sun's heat, air was formed; and as a consequence, the whole heaven grew by the fact that air, being more rarified, occupies more place than the water from which it is generated; what has been thus resolved out of water is the cause of winds and of the heaven's movement. Both, therefore, of these opinions are destroyed by the fact that we plainly see the return to earth, of whatever has been lifted upward from the water. And if it does not return to the same place and equally in all places (for in some regions there is more evaporation than rainfall), yet in various places, according to a certain order of time, all the matter that has been borne aloft returns again to earth. And so it is plainly not so that higher bodies are fed by vapors or that one portion of the vapors remains air and another returns to water.
Deinde cum dicit: potabile quidem igitur etc., ex eo quod supra praemissum est, concludit solutionem praedictae dubitationis. Et dicit quod cum vapor elevetur superius, illud quidem quod est dulce et potabile, totum elevatur superius, propter id quod est levius: illud autem quod est salsum, quia gravius est, manet deorsum, quasi in proprio loco. Hoc enim videtur rationabiliter et convenienter esse dictum in praemissa dubitatione, scilicet quod mare est locus naturalis aquae: irrationabile enim est si aqua non habeat proprium locum naturalem, sicut alia elementa. Sed solutio motae dubitationis contra hoc ex salsedine aquae, est quod locus quem mare occupat, est locus naturalis aquae, inquantum aqua: sed tamen videtur esse locus naturalis aquae maris solum, propter hoc quod salsum manet deorsum propter gravitatem, dulce autem evaporavit sursum propter levitatem. 153. Then [156] he concludes the solution of the aforesaid doubt, and says that since vapor is borne aloft, that which is sweet and drinkable is wholly carried up because of being lighter, whereas that which is salty, being heavier, remains below as in its proper place. For it seems to be reasonably and fittingly held in the difficulty previously set down that the sea is the natural place of water — for it is unreasonable that water should not have a proper natural place as do the other elements. But the solution of the difficulty raised against this from the saltiness of the sea is that the place occupied by the sea is the natural place of water qua water; whereas it seems to be the natural place of sea water only, because that which is salt remains below because of its heaviness, while the sweet is evaporated aloft, because of its lightness.
Et ponit exemplum de eo quod accidit in corporibus animalium. Quia, cum cibus assumptus sit dulcis et humidus, hypostasis quae remanet ex cibo, et superfluum alimenti, apparet amarum et salsum, propterea quia illud quod est dulce, est attractum a calore naturali ad carnem et ad quamlibet partem corporis, sicut quaelibet apta nata est nutriri. Per hoc ergo concludit a simili quod, sicut inconveniens esset si quis putaret quod venter non esset locus cibi, sed solum superfluitatis, quia dum nutriuntur membra, cito sumitur materia cibi, et superfluum remanet; sed tamen iste non bene existimaret, quia, ut prius diximus, iste est locus naturalis cibi, inquantum cibus, et non solum cibi in ventre existentis: similiter et in proposito iste locus occupatus a mari, est locus naturalis aquae. Et omnis aqua movetur ad ipsum tanquam ad locum proprium: fluxus enim aquae est ad id quod est magis concavum, et talis est locus maris. Sed quamvis locus iste sit naturalis aquae, tamen illud quod est dulce, cito fertur sursum, propter solem elevantem vaporem: illud autem quod est salsum, remanet inferius propter praedictam causam. He gives an example based on what happens in the bodies of animals. Although the food taken in is sweet and moist, the residue that remains of the food, as well as the superfluous nutriment, appears bitter and salty, because the sweet element has been drawn to flesh and to every part of the body by natural heat, according as each several part is naturally apt to be nourished. By analogy to this, he concludes that, just as it would be strange for a person to suppose that the belly is not the place of food but only of the residue, on the ground that when the members are being nourished, the matter of the food is forthwith removed from the belly and the residue remains, and such a person would not be judging wisely, because, as we have already said, it is the natural place of food qua food, and not just of the food present in the belly, so too at present, the place occupied by the sea is the natural place of water. Indeed, all water moves toward the sea as to its proper place; for the flow of water is toward what is more concave, as is the place of the sea. But although this is the natural place of water, yet what is sweet is forthwith borne aloft, because of the sun raising the vapor, while what is salty remains below for the reason already given.

Lecture 3
Why the sea does not increase. Rejection of Plato's Tartarus
Chapter 2 cont.
τὸ δὲ ζητεῖν τὴν ἀρχαίαν ἀπορίαν, διὰ τί τοσοῦτον πλῆθος ὕδατος οὐδαμοῦ φαίνεται (καθ' ἑκάστην γὰρ ἡμέραν ποταμῶν ῥεόντων ἀναρίθμων καὶ τὸ μέγεθος ἀπλέτων οὐδὲν ἡ θάλαττα γίγνεται πλείων), 157 It is quite natural that some people should have been puzzled by the old question why such a mass of water leaves no trace anywhere (for the sea does not increase though innumerable and vast rivers are flowing into it every day.)
τοῦτο οὐδὲν μὲν ἄτοπον ἀπορῆσαί τινας, οὐ μὴν ἐπιβλέψαντά γε χαλεπὸν ἰδεῖν. τὸ γὰρ αὐτὸ πλῆθος ὕδατος εἰς πλάτος τε διαταθὲν καὶ ἀθρόον οὐκ ἐν ἴσῳ χρόνῳ ἀναξηραίνεται, ἀλλὰ διαφέρει τοσοῦτον ὥστε τὸ μὲν διαμεῖναι ἂν ὅλην τὴν ἡμέραν, τὸ δ' ὥσπερ εἴ τις ἐπὶ τράπεζαν μεγάλην περιτείνειεν ὕδατος κύαθον, ἅμα διανοουμένοις ἂν ἀφανισθείη πᾶν. ὃ δὴ καὶ περὶ τοὺς ποταμοὺς συμβαίνει συνεχῶς γὰρ ῥεόντων ἀθρόων ἀεὶ τὸ ἀφικνούμενον εἰς ἀχανῆ καὶ πλατὺν τόπον ἀναξηραίνεται ταχὺ καὶ ἀδήλως. 158 But if one considers the matter the solution is easy. The same amount of water does not take as long to dry up when it is spread out as when it is gathered in a body, and indeed the difference is so great that in the one case it might persist the whole day long while in the other it might all disappear in a moment—as for instance if one were to spread out a cup of water over a large table. This is the case with the rivers: all the time they are flowing their water forms a compact mass, but when it arrives at a vast wide place it quickly and imperceptibly evaporates.
τὸ δ' ἐν τῷ Φαίδωνι γεγραμμένον περί τε τῶν ποταμῶν καὶ τῆς θαλάττης ἀδύνατόν ἐστιν. λέγεται γὰρ ὡς ἅπαντα μὲν εἰς ἄλληλα συντέτρηται ὑπὸ γῆν, ἀρχὴ δὲ πάντων εἴη καὶ πηγὴ τῶν (356a.) ὑδάτων ὁ καλούμενος Τάρταρος, περὶ τὸ μέσον ὕδατός τι πλῆθος, ἐξ οὗ καὶ τὰ ῥέοντα καὶ τὰ μὴ ῥέοντα ἀναδίδωσιν πάντα τὴν δ' ἐπίρρυσιν ποιεῖν ἐφ' ἕκαστα τῶν ῥευμάτων διὰ τὸ σαλεύειν ἀεὶ τὸ πρῶτον καὶ τὴν ἀρχήν οὐκ ἔχειν γὰρ ἕδραν, ἀλλ' ἀεὶ περὶ τὸ μέσον εἱλεῖσθαι κινούμενον δ' ἄνω καὶ κάτω ποιεῖν τὴν ἐπίχυσιν τοῖς ῥεύμασιν. τὰ δὲ πολλαχοῦ μὲν λιμνάζειν, οἷον καὶ τὴν παρ' ἡμῖν εἶναι θάλατταν, πάντα δὲ πάλιν κύκλῳ περιάγειν εἰς τὴν ἀρχήν, ὅθεν ἤρξαντο ῥεῖν, πολλὰ μὲν κατὰ τὸν αὐτὸν τόπον, τὰ δὲ καὶ καταντικρὺ τῇ θέσει τῆς ἐκροῆς, οἷον εἰ ῥεῖν ἤρξαντο κάτωθεν, ἄνωθεν εἰσβάλλειν. εἶναι δὲ μέχρι τοῦ μέσου τὴν κάθεσιν τὸ γὰρ λοιπὸν πρὸς ἄναντες ἤδη πᾶσιν εἶναι τὴν φοράν. τοὺς δὲ χυμοὺς καὶ τὰς χρόας ἴσχειν τὸ ὕδωρ δι' οἵας ἂν τύχωσι ῥέοντα γῆς. 159 But the theory of the Phaedo about rivers and the sea is impossible. There it is said that the earth is pierced by intercommunicating channels and that the original head and source of all waters is what is called Tartarus—a mass of water about the centre, from which all waters, flowing and standing, are derived. This primary and original water is always surging to and fro, and so it causes the rivers to flow on this side of the earth's centre and on that; for it has no fixed seat but is always oscillating about the centre. Its motion up and down is what fills rivers. Many of these form lakes in various places (our sea is an instance of one of these), but all of them come round again in a circle to the original source of their flow, many at the same point, but some at a point opposite to that from which they issued; for instance, if they started from the other side of the earth's centre, they might return from this side of it. They descend only as far as the centre, for after that all motion is upwards. Water gets its tastes and colours from the kind of earth the rivers happened to flow through.
συμβαίνει δὲ τοὺς ποταμοὺς ῥεῖν οὐκ ἐπὶ ταὐτὸν ἀεὶ κατὰ τὸν λόγον τοῦτον ἐπεὶ γὰρ εἰς τὸ μέσον εἰσρέουσιν ἀφ' οὗπερ ἐκρέουσιν, οὐδὲν μᾶλλον ῥευσοῦνται κάτωθεν ἢ ἄνωθεν, ἀλλ' ἐφ' ὁπότερ' ἂν ῥέψῃ κυμαίνων ὁ Τάρταρος. καίτοι τούτου συμβαίνοντος γένοιτ' ἂν τὸ λεγόμενον ἄνω ποταμῶν ὅπερ ἀδύνατον. 160 But on this theory rivers do not always flow in the same sense. For since they flow to the centre from which they issue forth they will not be flowing down any more than up, but in whatever direction the surging of Tartarus inclines to. But at this rate we shall get the proverbial rivers flowing upwards, which is impossible.
ἔτι τὸ γιγνόμενον ὕδωρ καὶ τὸ πάλιν ἀναγόμενον πόθεν ἔσται; τοῦτο γὰρ ἐξαίρειν ὅλον ἀναγκαῖον, εἴπερ ἀεὶ σῴζεται τὸ ἴσον ὅσον γὰρ ἔξω ῥεῖ, πάλιν ῥεῖ πρὸς τὴν ἀρχήν. 161 Again, where is the water that is generated and what goes up again as vapour to come from? For this must all of it simply be ignored, since the quantity of water is always the same and all the water that flows out from the original source flows back to it again.
καίτοι πάντες οἱ ποταμοὶ φαίνονται τελευτῶντες εἰς τὴν θάλατταν, ὅσοι μὴ εἰς ἀλλήλους εἰς δὲ γῆν οὐδείς, ἀλλὰ κἂν ἀφανισθῇ, πάλιν ἀναδύνουσιν. 162 This itself is not true, since all rivers are seen to end in the sea except where one flows into another. Not one of them ends in the earth, but even when one is swallowed up it comes to the surface again.
μεγάλοι δὲ γίγνονται τῶν ποταμῶν οἱ μακρὰν ῥέοντες διὰ κοίλης πολλῶν γὰρ δέχονται ῥεύματα ποταμῶν, ὑποτεμνόμενοι τῷ τόπῳ καὶ τῷ μήκει τὰς ὁδούς διόπερ ὅ τ' Ἴστρος καὶ ὁ Νεῖλος μέγιστοι τῶν ποταμῶν εἰσιν τῶν εἰς τήνδε τὴν θάλατταν ἐξιόντων. καὶ περὶ τῶν πηγῶν ἄλλοι λέγουσιν ἑκάστου τῶν ποταμῶν ἄλλας αἰτίας διὰ τὸ πολλοὺς εἰς τὸν αὐτὸν ἐμβάλλειν. 163 And those rivers are large which flow for a long distance through a lowying country, for by their situation and length they cut off the course of many others and swallow them up. This is why the Istrus and the Nile are the greatest of the rivers which flow into our sea. Indeed, so many rivers fall into them that there is disagreement as to the sources of them both.
ταῦτα δὴ πάντα φανερὸν ὡς ἀδύνατόν ἐστι συμβαίνειν ἄλλως τε καὶ τῆς θαλάττης ἐκεῖθεν τὴν ἀρχὴν ἐχούσης. 164 All of which is plainly impossible on the theory, and the more so as it derives the sea from Tartarus.
ὅτι μὲν οὖν ὕδατός τε ὁ τόπος ἐστὶν οὗτος καὶ οὐ θαλάττης, καὶ διὰ τίν' αἰτίαν τὸ μὲν πότιμον ἄδηλον πλὴν ῥέον, τὸ δ' ὑπομένον, καὶ διότι τελευτὴ (356b.) μᾶλλον ὕδατος ἢ ἀρχή ἐστιν ἡ θάλαττα, καθάπερ τὸ ἐν τοῖς σώμασιν περίττωμα τῆς τροφῆς πάσης, καὶ μάλιστα τὸ τῆς ὑγρᾶς, εἰρήσθω τοσαῦθ' ἡμῖν. 165 Enough has been said to prove that this is the natural place of water and not of the sea, and to explain why sweet water is only found in rivers, while salt water is stationary, and to show that the sea is the end rather than the source of water, analogous to the residual matter of all food, and especially liquid food, in animal bodies.
Hic philosophus movet aliam dubitationem, contra hoc quod dictum est quod mare est terminus fluviorum. Et circa hoc tria facit. 154. Here the Philosopher raises another doubt, against the position that the sea is the terminal of rivers. About this he does three things:
Primo movet dubitationem, quam dicit esse antiquam: propter quid scilicet, cum singulis diebus flumina et innumerabilia numero et immensa magnitudine intrent in mare, non tamen videtur crescere; et hoc in ipso non apparet, quod tanta multitudo aquae ad ipsum deveniat. First, he raises the doubt which he says is an old one [157]: namely, why is it that, whereas rivers without number and of immense size enter the sea every day, it does not seem to grow and gives no evidence that such a vast amount of water is flowing into it?
Secundo ibi: hoc quidem nullum etc., solvit dubitationem. Et dicit quod, licet non sit inconveniens quod sint aliqui qui circa hoc dubitent, tamen, si quis recte consideret, non est difficile videre solutionem huius. Quia si aliqua aqua diffundatur per aliquam latitudinem, supposito quod sit eadem multitudo aquae in diversis locis diffusa, si non sit eadem quantitas latitudinis, non est aequale tempus desiccationis aquae effusae; sed erit differentia ex diversitate latitudinis in qua aqua diffunditur, quod aliquando manet aqua et non exsiccatur per totum diem, aliquando autem statim ad oculum exsiccatur; sicut si aliquis unum scyphum aquae diffunderet super magnam mensam, statim tota aqua assiccaretur, si autem in aliquo parvo loco tantum de aqua proiiceretur, diu conservaretur. Sic igitur accidit circa fluvios et mare: nam totum quod ex fluviis ad mare pervenit, dispergitur in locum maximae latitudinis, et cito insensibiliter desiccatur per continuam evaporationem aquae, de qua supra dictum est. 155. Secondly [158], he solves the problem and says that, although it is not unfitting that some should be puzzled at this, yet, after careful consideration, it is not difficult to see the solution. Thus, if an amount of water is poured over a certain surface, and the same volume is poured out in different areas, then, if the size of the surface is not the same, the time required for the drying-up of the water poured out is not equal, but there will be a difference arising from the difference of surface on which the water is poured, so that sometimes the water remains and does not dry up for a whole day, while sometimes it dries up under one's very eyes. For example, if someone should pour a cup of water upon a large table, all the water would dry up at once; but if the same amount were poured into some small place, it would be preserved for a long time. This is what happens with rivers and the sea: for the total water coming from the rivers to the sea is spread out over an area of the greatest latitude, and is forthwith imperceptibly dried up by the continuous evaporation of water, concerning which we spoke above.
Tertio ibi: quod autem scriptum est in Phaedone etc., excludit quandam falsam solutionem praedictae dubitationis. 156. Thirdly [159], he excludes a certain false solution to this problem.
Et primo ponit ipsam solutionem. Et dicit quod impossibile est esse verum quod a Platone de mari et fluviis dicitur in libro suo qui intitulatur Phaedo. Dicit enim ibi quod omnia flumina et mare concurrunt sub terra ad aliquod principium, quasi terra sit perforata a mari et fluviis. Hoc autem principium, quod secundum ipsum est principium aquarum omnium, vocatur Tartarus, qui est quaedam magna multitudo aquae existens circa medium mundi: ex quo quidem principio dicit prodire omnes aquas quae non fluunt, sicut sunt mare et stagna, et quae fluunt, sicut fontes et flumina. Dicit autem quod Tartarus undique fluit ad singula rheumatum, idest ad singulos discursus aquarum: quod ideo contingit, quia illud principium aquarum semper movetur. Et hoc ideo, quia non habet aliquem locum fixum in quo quiescat, sed semper movetur circa medium, quasi vacillans hinc inde. Et sic, dum movetur sursum, facit effusionem rheumatum, idest discursus marium et fluviorum, non tantum versus istam partem terrae quam nos habitamus; sed ex multis aliis partibus terrae effundit et alia stagna, quale est mare quod est apud nos. First, he gives the solution and says that what Plato says about the sea and rivers in his book entitled the Phaedo , cannot be true. For he says there that all rivers and the sea meet at a source under the earth, as though the earth were perforated by the sea and rivers. This source, which according to him, is the source of all waters, is called "Tartarus," a certain vast body of water existing about the center of the world: from it, he says, come all the waters that do not flow, such as the sea and ponds, and waters that do flow, such as springs and rivers. He says further that Tartarus flows in every direction to each of the rheums," i.e., to each of the streams of water. This happens because that source of all waters is forever in motion, for it has no fixed place in which to rest but is forever in motion about the center, as though wandering to and fro. Thus, when it is surging upward, it produces the "flowing out of rheums," i.e., the streaming of seas and rivers, not only toward that portion of the earth we inhabit; but from many other parts of the earth it pours out other bodies of still water, akin to the sea which exists among us.
Sed omnia maria et flumina quadam circulatione reducuntur ad illud principium unde primo effluxerunt, sed diversimode. Nam quaedam redeunt secundum eundem locum secundum quem effluxerunt, ut sit quidam motus reflexus: quaedam vero ex contraria parte redeunt parti unde effluxerant, ut, puta, si effluxerunt de subtus, reingrederentur desuper. Non est tamen sic intelligendum de subtus et desuper, quod aliquid possit esse subtus respectu medii, in quo ponitur primum principium aquarum: quia a superficie terrae usque ad medium, est descensus, sed de cetero, si secundum rectam lineam ultra procederet aqua, esset motus ad sursum; idem enim est moveri a medio, et moveri sursum. But all seas and rivers are brought back by a certain cycle to that source whence they emerged, but in various ways. For some return according to the same place whence they flowed out, by a kind of reflex movement; others return along a route contrary to the one along which they emerged, so that, for example, if they emerged from beneath, they would flow back from above. We should not so think of "above" and "beneath" as to think that something could be beneath with respect to the center in which the primal source of waters is postulated: for from the surface of the earth to the center, there is a descent; but further, if the water should proceed beyond in a straight line, the course would be upward — movement from the center being the same as movement upward.
Et secundum hoc facile est assignare causam diversitatis colorum et saporum in aquis: quia aqua fluens recipit colorem et saporem secundum modum terrae per quam effluit. And according to this it is easy to assign a cause for the various colors and tastes of water: because the flowing water acquires its color and taste from the type of earth through which it flows out.
Secundo ibi: accidit ergo fluvios etc., improbat praedictam positionem quinque rationibus. 157. Secondly [160], he disposes of the aforesaid position with five reasons.
Quarum prima est quod, cum quandoque flumina redeant per eandem viam, quandoque autem per contrariam, sequitur secundum hanc positionem quod fluviorum fluxus non semper fit ad eandem partem. Quia enim redeunt ad medium a quo fluxerunt, non magis fluent subtus quam supra, comparando superficiem terrae ad medium, quod semper intelligitur: a superficie terrae vocatur aliquid sursum et aliquid deorsum, propter altitudinem et demissionem. Si enim motus fluviorum causatur ex effluentia Tartari, effluentia autem Tartari est ad omnem partem, sequitur quod aqua, quasi impulsa a Tartaro, indifferenter fluat ad quamlibet partem, sicut et Tartarus fluctuans tendit ad omnem partem. Et sic accidet illud quod dicitur in proverbio, sursum fluviorum, scilicet quod flumina sint superiora fontibus, vel quod sursum fluant: et hoc est impossibile. The first is that, since sometimes the rivers return by the same route and sometimes by a contrary one, it follows, according to this position, that the flow of rivers is not consistently in the same direction. For since they return to the center from which they flowed, they will not flow "below" any more than "above," if you compare the surface of the earth to the center, as is always understood. But in relation to the surface of the earth something is "up," and something "down," depending on height and depth. If the movement of rivers is caused from Tartarus' overflow and this overflow is in every direction, it follows that the water, impelled, as it were, by Tartarus, flows indiscriminately in every direction, just as Tartarus in its fluctuation goes in every direction. Consequently, what is said in the proverb will come to pass, namely, an "up" of rivers, i.e., rivers that are higher than the springs or that flow uphill — which is impossible.
Secundam rationem ponit ibi: adhuc quae fit aqua etc.: quae talis est. Secundum praedictam positionem, videtur quod oporteat semper aequalem aquam salvari: quia quantum fluit de aqua a Tartaro, tantum ponit quod iterum refluat ad principium. Et sic oportet totaliter excludere generationem aquae in aere, et elevationem aquae a terra per evaporationem: quod patet esse falsum. He presents the second reason [161], namely, that, according to the aforesaid position, it is seen that it would be necessary that an equal amount of water be always preserved — for he posits that as much water as flows from Tartarus returns to the source. Consequently, one must entirely exclude generation of water in the air and elevation of water from the earth by vaporizing — which is plainly false.
Tertiam rationem ponit ibi: quamvis omnes fluvii et cetera. Et est quod omnes fluvii terminantur ad mare, quicumque non terminantur ad alios fluvios; et nullum flumen est sic terminatum ad terram, quasi terram perforans, quod vadat ad Tartarum; sed si sunt aliqua flumina intrantia in concavitatem terrae, iterum exeunt in aliquo loco. Et sic non videtur verum quod flumina iterum redeant ad Tartarum. He presents the third reason [162], namely, that all rivers end at the sea which do not terminate at other rivers, and no river so ends in the earth as though perforating the earth and going to Tartarus. Indeed, if there are any rivers entering into the concavity of the earth, they emerge again at some other spot. Consequently, it is not seen to be true that rivers return to Tartarus.
Quartam rationem ponit ibi: magni autem fiunt etc.: quae talis est. Si cursus fluviorum causatur ex effluentia Tartari, oporteret quod ab ipso sui principio flumina multitudinem aquae haberent. Sed hoc non videmus: quia inter fluvios illi inveniuntur magni, qui per longam viam fluunt, eo quod recipiunt discursiones multorum fluviorum, et detruncant vias eorum et secundum locum, quia sunt profunda magis et magis concava, et secundum longitudinem, quia longiorem viam currunt. Et ideo Ister, idest Danubius, et Nilus sunt maximi fluviorum qui in mare Mediterraneum exeunt; et de fontibus eorum diversi diversa dicunt, propter diversitatem fluviorum qui in hos intrant. The fourth reason which he presents [163] is this: if the course of rivers is caused by what flows out of Tartarus, it would be necessary that rivers have a vast abundance of water from the very start. But this we do not observe: among rivers, those are found to be large which flow a long course, since they receive the flowings of many rivers and cut off their route both as to place, because they are deeper and more concave, and as to length, because they follow a longer course. This is why the Ister, i.e., the Danube, and the Nile are the largest rivers flowing into the Mediterranean Sea, and concerning their sources different ones say different things, because of the variety of rivers that enter them.
Quintam rationem ponit ibi: haec itaque et cetera. Et est quod, ultra praedicta inconvenientia, est etiam hoc, quod sequeretur quod mare habeat principium a Tartaro. Quod inconveniens est: quia mare videtur esse locus naturalis aquarum, sicut supra dictum est. He presents the fifth reason [164], namely, that over and above the unacceptable aspects already indicated, there is also the fact that it would follow that the sea has its source from Tartarus. And this is not fitting, because, as has been said, the sea is seen to be the natural place of water.
Tertio ibi: quod quidem igitur etc., recolligit quae supra dicta sunt. Et dicit quod tanta dicta sint de hoc quod locus iste quem mare occupat, est locus naturalis aquae, et non solum locus naturalis maris, idest aquae salsae existentis. Et dictum est quare illud quod est potabile et dulce, non manifestatur in mari, sed in aquis fluentibus; illud autem quod salsum est, subsidet in mari, quasi derelictum post evaporationem eius quod erat potabile et dulce. Et dictum est etiam quod mare magis est terminus aquarum quam principium: quia scilicet aqua extra mare generatur, et sursum in aere, ut dictum est de generatione pluviarum, et intra terram, ut dictum est de generatione fontium et fluviorum; et tamen, ubicumque generatur aqua, fluit ad mare, nisi impediatur. Et sic aqua salsa se habet sicut illud quod est superfluum alimenti in corporibus animalium: nam superfluum alimenti est salsum vel amarum. Quod verum est de superfluo cuiuslibet alimenti, sed maxime de superfluo alimenti humidi, sicut urina, quae est magis indigesta, et ideo est magis amara et salsa, ut patet. 158. Thirdly [165], he brings together what has been said above. And he says that so much has been said about the fact that the place which the sea occupies is the natural place of water and not just the natural place of the "sea," i.e., of salt water. And it has been stated why what is drinkable and sweet does not show up in the sea but does in flowing water: what is salty subsides in the sea, being, as it were, the residue from the evaporation of what is drinkable and sweet. Furthermore, it has been said that the sea is rather the end than the source of waters: since, namely, water is generated outside the sea, both in the air above (as was said of the generation of rain), and within the earth (as was said of the generation of springs and rivers); nevertheless, no matter where it is generated, water flows to the sea, unless it is prevented. And thus, salt water is akin to the residue of food in the bodies of animals: for the residue of food is salty and bitter. This is true of the residue of any food, but especially of moist food, as in the case of urine, which is more undigested and therefore more bitter and salty, as is evident.

Lecture 4
Whether the sea always, was, and always will be
Chapter 3
περὶ δὲ τῆς ἁλμυρότητος αὐτῆς λεκτέον, καὶ πότερον αἰεί ἐστιν ἡ αὐτή, ἢ οὔτ' ἦν οὔτ' ἔσται ἀλλ' ὑπολείψει καὶ γὰρ οὕτως οἴονταί τινες. 166 We must now explain why the sea is salt, and ask whether it eternally exists as identically the same body, or whether it did not exist at all once and some day will exist no longer, but will dry up as some people think.
τοῦτο μὲν οὖν ἐοίκασι πάντες ὁμολογεῖν, ὅτι γέγονεν, εἴπερ καὶ πᾶς ὁ κόσμος ἅμα γὰρ αὐτῆς ποιοῦσι τὴν γένεσιν. ὥστε δῆλον ὡς εἴπερ ἀίδιον τὸ πᾶν, καὶ περὶ τῆς θαλάττης οὕτως ὑποληπτέον. 167 Every one admits this, that if the whole world originated the sea did too; for they make them come into being at the same time. It follows that if the universe is eternal the same must be true of the sea.
τὸ δὲ νομίζειν ἐλάττω τε γίγνεσθαι τὸ πλῆθος, ὥσπερ φησὶ Δημόκριτος, καὶ τέλος ὑπολείψειν, τῶν Αἰσώπου μύθων οὐδὲν διαφέρειν ἔοικεν ὁ πεπεισμένος οὕτως καὶ γὰρ ἐκεῖνος ἐμυθολόγησεν ὡς δὶς μὲν ἡ Χάρυβδις ἀναρροφήσασα τὸ μὲν πρῶτον τὰ ὄρη ἐποίησεν φανερά, τὸ δὲ δεύτερον τὰς νήσους, τὸ δὲ τελευταῖον ῥοφήσασα ξηρὰν ποιήσει πάμπαν. ἐκείνῳ μὲν οὖν ἥρμοττεν ὀργιζομένῳ πρὸς τὸν πορθμέα τοιοῦτον εἰπεῖν μῦθον, τοῖς δὲ τὴν ἀλήθειαν ζητοῦσιν ἧττον 168 Any one who thinks like Democritus that the sea is diminishing and will disappear in the end reminds us of Aesop's tales. His story was that Charybdis had twice sucked in the sea: the first time she made the mountains visible; the second time the islands; and when she sucks it in for the last time she will dry it up entirely. Such a tale is appropriate enough to Aesop in a rage with the ferryman, but not to serious inquirers.
δι' ἣν γὰρ αἰτίαν ἔμεινε τὸ πρῶτον, εἴτε διὰ βάρος, ὥσπερ τινὲς καὶ τούτων φασίν (ἐν προχείρῳ γὰρ τούτου τὴν αἰτίαν ἰδεῖν), εἴτε καὶ δι' ἄλλο τι, δῆλον ὅτι διὰ τοῦτο διαμένειν ἀναγκαῖον καὶ τὸν λοιπὸν χρόνον αὐτήν. ἢ γὰρ λεκτέον αὐτοῖς ὅτι οὐδὲ τὸ ἀναχθὲν ὕδωρ ὑπὸ τοῦ ἡλίου ἥξει πάλιν, ἢ εἴπερ τοῦτ' ἔσται, ἀναγκαῖον ἤτοι ἀεὶ ἢ μέχρι οὗπερ ἂν ᾖ τοῦτο ὑπολείπεσθαι τὴν θάλατταν, καὶ πάλιν ἀναχθῆναι ἐκεῖνο πρότερον δεήσει τὸ πότιμον. ὥστε οὐδέποτε ξηρανεῖται πάλιν γὰρ ἐκεῖνο φθήσεται καταβὰν εἰς τὴν αὐτὴν τὸ προανελθόν διαφέρει γὰρ οὐδὲν ἅπαξ τοῦτ' εἰπεῖν ἢ πολλάκις. εἰ μὲν οὖν τὸν ἥλιον παύσει τις τῆς φορᾶς, τί ἔσται τὸ ξηραῖνον; εἰ δ' ἐάσει εἶναι τὴν περιφοράν, ἀεὶ πλησιάζων τὸ πότιμον, καθάπερ εἴπομεν, ἀνάξει, ἀφήσει δὲ πάλιν ἀναχωρῶν. 169 Whatever made the sea remain at first, whether it was its weight, as some even of those who hold these views say (for it is easy to see the cause here), or some other reason—clearly the same thing must make it persist for ever. They must either deny that the water raised by the sun will return at all, or, if it does, they must admit that the sea persists for ever or as long as this process goes on, and again, that for the same period of time that sweet water must have been carried up beforehand. So the sea will never dry up: for before that can happen the water that has gone up beforehand will return to it: for if you say that this happens once you must admit its recurrence. If you stop the sun's course there is no drying agency. If you let it go on it will draw up the sweet water as we have said whenever it approaches, and let it descend again when it recedes.
ἔλαβον δὲ ταύτην τὴν διάνοιαν κατὰ τῆς θαλάττης ἐκ τοῦ πολλοὺς τόπους φαίνεσθαι ξηροτέρους νῦν ἢ πρότερον περὶ οὗ τὴν αἰτίαν εἴπομεν, ὅτι τῶν κατά τινα χρόνον ὑπερβολῶν γιγνομένων ὕδατος τοῦτ' ἐστὶν τὸ πάθος, ἀλλ' οὐ διὰ τὴν τοῦ παντὸς γένεσιν καὶ τῶν μορίων καὶ πάλιν γ' ἔσται τοὐναντίον καὶ (357a.) ὅταν γένηται, ξηρανεῖται πάλιν καὶ τοῦθ' οὕτως κατὰ κύκλον ἀναγκαῖον ἀεὶ βαδίζειν μᾶλλον γὰρ οὕτως εὔλογον ὑπολαβεῖν ἢ διὰ ταῦτα τὸν οὐρανὸν ὅλον μεταβάλλειν. ἀλλὰ περὶ μὲν τούτων πλείω τῆς ἀξίας ἐνδιατέτριφεν ὁ λόγος 170 This notion about the sea is derived from the fact that many places are found to be drier now than they once were. Why this is so we have explained. The phenomenon is due to temporary excess of rain and not to any process of becoming in which the universe or its parts are involved. Some day the opposite will take place and after that the earth will grow dry once again. We must recognize that this process always goes on thus in a cycle, for that is more satisfactory than to suppose a change in the whole world in order to explain these facts. But we have dwelt longer on this point than it deserves.
Postquam philosophus determinavit de natura maris, ostendens quod est locus naturalis aquae, hic inquirit de generatione ipsius. 159. After determining the nature of the sea, showing that it is the natural place of water, the Philosopher here inquires into its generation.
Et primo dicit de quo est intentio. Et dicit quod dicendum est de salsedine maris; et iterum utrum mare est sempiternum, aut fuit aliquod tempus quando non erat mare, et erit aliquod tempus quo non erit, sed totaliter deficiet. First, he indicates his intention [166], and says that we must speak about the salt of the sea, and furthermore, about whether the sea is eternal or whether there was a time when the sea was not, and there will be a time when the sea will not be, but will completely cease.
Secundo ibi: etenim sic putant quidam etc., prosequitur propositum, destruendo opiniones aliorum circa hoc. 160. Secondly, he pursues the proposition by disproving the theories of others on this matter:

Et primo destruit opiniones antiquorum;

secundo excludit rationem eorum, ibi: acceperunt autem suspicionem hanc et cetera.

First, he disproves the theories of the ancients;

Secondly, he excludes their reason, at 163.

Circa primum duo facit. About the first he does two things:
Primo destruit opiniones antiquorum de incoeptione maris. Et dicit quod quidam putaverunt quod mare non semper fuit, sed quandoque incoepit: et posuerunt etiam quod totus mundus esse incoepit per generationem quandam, dicentes quod simul generatum est mare cum mundo. Et hoc rationabiliter: quia cum mare sit aliquo modo locus aquae, quae est unum elementum, oportet quod sit de principalibus partibus mundi; et ideo quandocumque fuit mundus, fuit mare. Et ideo, sicut illi argumentantur quod, quia mundus genitus est, et mare sit generatum, ita possumus e converso argumentari quod, si mundus est perpetuus, et mare sit perpetuum. Quod autem mundus sit perpetuus, praesupponit ex his quae probavit in libro Physic. et in libro de caelo; quamvis hoc sit falsum et alienum a fide, ut supra dictum est. First, he disproves the theories of the ancients about the sea's coming into existence [167] and says that some have thought that the sea has not always existed but began to exist at some time. They also posited that the entire world began to exist as the result of some process of generation and stated that the sea began with the world. This was not unreasonable, since, the sea being in a sense the place of water, which is one element, it must be among the principal parts of the world. Hence, whenever the world existed, the sea did. And therefore, just as they argue that, because the world was generated, the sea was generated, so we can argue conversely, that if the world is perpetual, so too is the sea. But that the world is perpetual, he presupposes from what he proved in the Physics and in On the Heavens — although this is false and alien to the faith, as was said above.
Secundo ibi: putare autem minus etc., destruit opiniones antiquorum de defectu maris. Et primo comparat opinionem istam opinionibus fabulosis. Et dicit quod putare hoc quod mare fiat minus secundum quantitatem, et tandem deficiat, secundum quod dixit Democritus, non differt a fabulosis opinionibus Aesopi, qui dixit fabulose quod Charybdis, quae est quaedam vorago in mari, bis absorbuit mare; ita quod ante aqua totam terram circumdabat, vorago autem tantum de aqua absorbuit, quod montes apparuerunt discooperti ab aquis, et terra quae interiacet montibus; secundo autem tantum de aqua absorbuit, quod apparuerunt insulae; ultimo autem absorbebit totam aquam maris, et sic undique remanebit terra arida sine mari. Sed licet componere fabulam talem congrueret Aesopo fabularum inventori, qui hoc dixit dum forte esset iratus ad porthmeum, idest ad quendam portum vel litus maris, ut, iratus aquis, quasi fingeret eas omnes esse absorbendas; tamen talia dicere philosophis inquirentibus veritatem minus convenit. 161. Secondly [168], he disproves the opinions of the ancients about the disappearance of the sea. First he compares this theory to fables. And he says that to think that the sea will diminish in size and at length disappear, as Democritus said, is no different than the ideas in the fables of Aesop, who stated in a fable that Charybdis, a certain deep chasm in the sea, has twice absorbed the sea, in such a manner that previously water covered the entire earth, and this chasm imbibed enough water for the mountains to appear, having been uncovered from the water, and also the land between them; the second time it took in enough for islands to appear; the final time, it will swallow all the water of the sea, and thus there will everywhere remain dry land without the sea. But although to compose such a fable befits Aesop, the inventor of fables, who uttered this one when perhaps in a fit of anger with a "porthmeum," i.e., some harbor or seashore, so that, being angry with the waters, he pretended that all waters were destined to be swallowed up, yet, the utterance of such tales is less fitting for philosophers seeking the truth.
Secundo ibi: propter quam causam etc., improbat praedictam positionem per rationem. Et dicit quod propter quamcumque causam aqua maris primo mansit circa terram, oportebit quod semper maneat: sive dicatur quod hoc accidit propter gravitatem aquae, quae pondere suo hoc habet quod subsideat aeri et praeemineat terrae, (quae quidem causa est vera et manifesta); sive quaecumque alia causa sit, propter hoc oportet quod, si aliquando fuit aqua maris super terram, quod semper maneat. Quia aliter, si hoc non esset, oporteret eos dicere quod aqua quae elevatur a sole evaporata, non redeat iterum ad terram; cuius contrarium manifeste videmus in pluviis. Aut si aqua elevata redit, necesse est vel quod semper duret mare, si aqua semper elevatur et redit; aut quod remaneat quandiu hoc fuerit, quod aqua redit. Et iterum oportebit ferri sursum per evaporationem illud quod est potabile in aqua. Et sic nunquam exsiccabitur mare in tali alternatione: quia iterum aqua descendet in mare. 162. Secondly [169], he disproves the aforesaid theory with a reason. And he says that whatever be the cause on account of which water first surrounded the earth, it will necessarily remain forever: whether it be said that this happens on account of the heaviness of water, whose weight makes it abide beneath the air and above the earth (which, indeed, is the true and manifest cause), or whatever else the cause may be, nevertheless, because of this, it must be that, if the water of the sea was at some time on the earth, it remain forever. For otherwise, if this were not so, they would have to say that the evaporated water borne aloft by the sun, does not return again to earth (the opposite of which is plain in the case of rain). Or, if the elevated water returns, it must needs be either that the sea always abide, if water is forever borne aloft and returns, or that it abide so long as the phenomenon of water returning shall continue. Further, it will be necessary for that which is drinkable in water to be borne aloft by evaporation. Consequently, the sea will never grow dry in such an alternation — since the water will return once more to the sea.
Et non differt utrum hoc semel fiat, scilicet quod aqua elevata iterum descendat, aut fiat saepe: quia utroque modo non minuitur aliquid de aqua. Quia scilicet posset dici quod haec alternatio non semper erit, motu solis cessante, ideo subiungit quod si aliquis dicat quod motus solis cesset, non remanebit aliquid quod possit exsiccare aquam maris: si autem motus solis semper maneat, oportebit quod semper sol, appropinquans ad aliquam partem terrae, elevet per evaporationem aquam; et quando longius recedit, eam cadere propter frigiditatem. Et sic non potest dici quod mare totaliter exsiccetur, sive motus solis cesset sive non. And it makes no difference whether this happens once, namely, that the elevated water descend again, or a number of times: for in either case, no water is lost. Because it could, however, be claimed that this alternating process will not last forever, if the movement of the sun were to cease, he therefore adds that if anyone should say that the motion of the sun will cease, there will be nothing left to cause the sea's drying up; but if the motion of the sun abides forever, then it will always be necessary that the sun, as it approaches some region of the earth, lift up water by evaporation, and, when it departs from that region, that the water should fall, by reason of the cold. And so it cannot be said that the sea will entirely dry out, whether the motion of the sun continues or ceases.
Deinde cum dicit: acceperunt autem suspicionem hanc etc., excludit rationem moventem eos ad hoc ponendum. Et dicit quod acceperunt hanc opinionem, quod scilicet totaliter exsiccaretur mare, et quod quandoque incoeperit, propter hoc quod multa loca apparent magis sicca nunc quam prius. Sed causa propter quam accidit haec passio, dicta est prius, quia scilicet secundum quaedam determinata tempora fiunt excessus aquarum: sed non accidit propter hoc quod totum universum generetur; sed eius partes generantur. Et iterum secundum alia determinata tempora erit contrarium, scilicet quod erit magnus excessus siccitatis; quod cum factum fuerit, iterum desiccabitur terra, quae erat cooperta aquis propter excessum aquarum prius factum. Et necesse est quod hoc semper procedat circulariter, scilicet quod post excessum aquarum, determinato tempore, fiat excessus siccitatis, et e converso. Rationabilius enim est sic opinari, quam ponere quod totum caelum permutetur, propter quasdam particulares permutationes existentes circa terram. 163. Then [170] he dismisses the reason moving them to posit their theory. And he says that they took up this theory (namely, that the sea would become wholly dry, and that it began at some time to exist), because there are many places that seem drier now than formerly. But the cause of this passion has not been given before, namely, the fact that at certain determinate times an excess of water is produced, and not because the universe as a whole is in the process of becoming — although its parts are. Then, at other determinate times, the contrary will come to pass, namely, there will be an excessive drought. When this shall have come about, the land will again be dried out which had been covered with water by the previous excess of water. And it is necessary that this proceed always in a cyclic way, namely, that after an excess of water there be, at a definite time, an excess of dryness, and vice-versa. This is more reasonable than the theory that the whole heaven is undergoing change just because of certain particular changes taking place around the earth.
Et quia praedicta positio, contra quam locutus est, in superficie rationabilis apparet, subiungit quod circa hoc immoratus est eius sermo plus quam dignum fuerit. And because this theory against which he has spoken appears reasonable on the surface, he remarks that his discussion has lingered longer on this point than it deserves.

Lecture 5
The saltness of the sea according to the opinions, of others
Chapter 3 cont.
περὶ δὲ τῆς ἁλμυρότητος, τοῖς μὲν ἅπαξ γεννήσασι καὶ ὅλως αὐτὴν γεννῶσιν ἀδύνατόν ἐστιν ἁλμυρὰν ποιεῖν. εἰ γὰρ παντὸς τοῦ ὑγροῦ τοῦ περὶ τὴν γῆν ὄντος καὶ ἀναχθέντος ὑπὸ τοῦ ἡλίου τὸ ὑπολειφθὲν ἐγένετο θάλαττα, εἴτ' ἐνυπῆρχε τοσοῦτος χυμὸς ἐν τῷ πολλῷ ὕδατι καὶ γλυκεῖ διὰ τὸ συμμειχθῆναί τινα γῆν τοιαύτην, οὐδὲν ἧττον ἐλθόντος πάλιν τοῦ διατμίσαντος ὕδατος ἀνάγκη, ἴσου γ' ὄντος τοῦ πλήθους, καὶ τὸ πρῶτον ἢ εἰ μηδὲ τὸ πρῶτον, μηδ' ὕστερον ἁλμυρὰν αὐτὴν εἶναι. εἰ δὲ καὶ τὸ πρῶτον εὐθὺς ἦν, λεκτέον τίς ἡ αἰτία, καὶ ἅμα διὰ τί οὐκ εἰ καὶ τότε ἀνήχθη καὶ νῦν πάσχει ταὐτό. 171 To return to the saltness of the sea: those who create the sea once for all, or indeed generate it at all, cannot account for its saltness. It makes no difference whether the sea is the residue of all the moisture that is about the earth and has been drawn up by the sun, or whether all the flavour existing in the whole mass of sweet water is due to the admixture of a certain kind of earth. Since the total volume of the sea is the same once the water that evaporated has returned, it follows that it must either have been salt at first too, or, if not at first, then not now either. If it was salt from the very beginning, then we want to know why that was so; and why, if salt water was drawn up then, that is not the case now.
ἀλλὰ μὴν καὶ ὅσοι τὴν γῆν αἰτιῶνται τῆς ἁλμυρότητος ἐμμειγνυμένην (ἔχειν γάρ φασι πολλοὺς χυμοὺς αὐτήν, ὥσθ' ὑπὸ τῶν ποταμῶν συγκαταφερομένην διὰ τὴν μεῖξιν ποιεῖν ἁλμυράν), ἄτοπον τὸ μὴ καὶ τοὺς ποταμοὺς ἁλμυροὺς εἶναι πῶς γὰρ δυνατὸν ἐν πολλῷ μὲν πλήθει ὕδατος ἐπίδηλον οὕτως ποιεῖν τὴν μεῖξιν τῆς τοιαύτης γῆς, ἐν ἑκάστῳ δὲ μή; δῆλον γὰρ ὅτι ἡ θάλαττά ἐστιν ἅπαν τὸ ποτάμιον ὕδωρ οὐδενὶ γὰρ διέφερεν ἀλλ' ἢ τῷ ἁλμυρὰ εἶναι τῶν ποταμῶν τοῦτο δ' ἐν ἐκείνοις ἔρχεται εἰς τὸν τόπον εἰς ὃν ἀθρόοι ῥέουσιν. 172 Again, if it is maintained that an admixture of earth makes the sea salt (for they say that earth has many flavours and is washed down by the rivers and so makes the sea salt by its admixture), it is strange that rivers should not be salt too. How can the admixture of this earth have such a striking effect in a great quantity of water and not in each river singly? For the sea, differing in nothing from rivers but in being salt, is evidently simply the totality of river water, and the rivers are the vehicle in which that earth is carried to their common destination.
ὁμοίως δὲ γελοῖον κἂν εἴ τις εἰπὼν ἱδρῶτα τῆς γῆς εἶναι τὴν θάλατταν οἴεταί τι σαφὲς εἰρηκέναι, καθάπερ Ἐμπεδοκλῆς πρὸς ποίησιν μὲν γὰρ οὕτως εἰπὼν ἴσως εἴρηκεν ἱκανῶς (ἡ γὰρ μεταφορὰ ποιητικόν), πρὸς δὲ τὸ γνῶναι τὴν φύσιν οὐχ ἱκανῶς οὐδὲ γὰρ ἐνταῦθα δῆλον πῶς ἐκ γλυκέος τοῦ πόματος ἁλμυρὸς γίγνεται ὁ ἱδρώς, πότερον ἀπελθόντος τινὸς μόνον οἷον τοῦ γλυκυτάτου, ἢ συμμειχθέντος τινός, καθάπερ ἐν τοῖς διὰ τῆς τέφρας ἠθουμένοις ὕδασιν. φαίνεται δὲ τὸ αἴτιον ταὐτὸ καὶ περὶ τὸ εἰς τὴν κύστιν περίττωμα συλλεγόμενον καὶ γὰρ ἐκεῖνο πικρὸν καὶ ἁλμυρὸν γίγνεται τοῦ πινομένου καὶ τοῦ ἐν τῇ τροφῇ ὑγροῦ (357b.) γλυκέος ὄντος. εἰ δὴ ὥσπερ τὸ διὰ τῆς κονίας ἠθούμενον ὕδωρ γίγνεται πικρόν, καὶ ταῦτα, τῷ μὲν οὔρῳ συγκαταφερομένης τοιαύτης τινὸς δυνάμεως οἵα καὶ φαίνεται ὑφισταμένη ἐν τοῖς ἀγγείοις ἁλμυρίς, τῷ δ' ἱδρῶτι συνεκκρινομένης ἐκ τῶν σαρκῶν, οἷον καταπλύνοντος τὸ τοιοῦτον ἐκ τοῦ σώματος τοῦ ἐξιόντος ὑγροῦ, δῆλον ὅτι κἀν τῇ θαλάττῃ τὸ ἐκ τῆς γῆς συγκαταμισγόμενον τῷ ὑγρῷ αἴτιον τῆς ἁλμυρότητος. ἐν μὲν οὖν τῷ σώματι γίγνεται τὸ τοιοῦτον ἡ τῆς τροφῆς ὑπόστασις διὰ τὴν ἀπεψίαν ἐν δὲ τῇ γῇ τίνα τρόπον ὑπῆρχε, λεκτέον. 173 It is equally absurd to suppose that anything has been explained by calling the sea 'the sweat of the earth', like Empedicles. Metaphors are poetical and so that expression of his may satisfy the requirements of a poem, but as a scientific theory it is unsatisfactory. Even in the case of the body it is a question how the sweet liquid drunk becomes salt sweat whether it is merely by the departure of some element in it which is sweetest, or by the admixture of something, as when water is strained through ashes. Actually the saltness seems to be due to the same cause as in the case of the residual liquid that gathers in the bladder. That, too, becomes bitter and salt though the liquid we drink and that contained in our food is sweet. If then the bitterness is due in these cases (as with the water strained through lye) to the presence of a certain sort of stuff that is carried along by the urine (as indeed we actually find a salt deposit settling in chamber-pots) and is secreted from the flesh in sweat (as if the departing moisture were washing the stuff out of the body), then no doubt the admixture of something earthy with the water is what makes the sea salt. Now in the body stuff of this kind, viz. the sediment of food, is due to failure to digest: but how there came to be any such thing in the earth requires explanation.
ὅλως δὲ πῶς οἷόν τε τοσοῦτον ὕδατος πλῆθος ξηραινομένης καὶ θερμαινομένης ἐκκριθῆναι; 174 Besides, how can the drying and warming of the earth cause the secretion such a great quantity of water; especially as that must be a mere fragment of what is left in the earth?
πολλοστὸν γὰρ δεῖ μέρος αὐτὸ τοῦ λειφθέντος εἶναι ἐν τῇ γῇ. ἔτι διὰ τί οὐ καὶ νῦν ὅταν ξηραινομένη τύχῃ γῆ, εἴτε πλείων εἴτε ἐλάττων, ἰδίει; (ἡ γὰρ ὑγρότης καὶ ὁ ἱδρὼς γίγνεται πικρός.) εἴπερ γὰρ καὶ τότε, καὶ νῦν ἐχρῆν. οὐ φαίνεται δὲ τοῦτο συμβαῖνον, ἀλλὰ ξηρὰ μὲν οὖσα ὑγραίνεται, ὑγρὰ δ' οὖσα οὐδὲν πάσχει τοιοῦτον. πῶς οὖν οἷόν τε περὶ τὴν πρώτην γένεσιν, ὑγρᾶς οὔσης τῆς γῆς, ἰδίειν ξηραινομένην; ἀλλὰ μᾶλλον εἰκός, ὥσπερ φασί τινες, ἀπελθόντος τοῦ πλείστου καὶ μετεωρισθέντος τοῦ ὑγροῦ διὰ τὸν ἥλιον, τὸ λειφθὲν εἶναι θάλατταν ὑγρὰν δ' οὖσαν ἰδίειν ἀδύνατον. τὰ μὲν οὖν λεγόμενα τῆς ἁλμυρότητος αἴτια διαφεύγειν φαίνεται τὸν λόγον 175 Again, waiving the question of quantity, why does not the earth sweat now when it happens to be in process of drying? If it did so then, it ought to do so now. But it does not: on the contrary, when it is dry it graws moist, but when it is moist it does not secrete anything at all. How then was it possible for the earth at the beginning when it was moist to sweat as it grew dry? Indeed, the theory that maintains that most of the moisture departed and was drawn up by the sun and that what was left over is the sea is more reasonable; but for the earth to sweat when it is moist is impossible.
Postquam philosophus determinavit de natura maris et eius generatione, nunc determinat de eius salsedine. 164. After determining about the nature of the sea and about its generation, the Philosopher now determines about its saltness.

Et primo inquirit de ea secundum opiniones aliorum;

secundo ponit suam opinionem, ibi: nos autem dicamus et cetera.

First, he inquires about it according to the opinions of others;

Secondly, he presents his own opinion (L. 6).

Circa primum, prosequitur de salsedine maris secundum tres opiniones philosophorum naturalium, in principio huius tractatus de mari positas. With respect to the first he continues with the salt of the sea according to the three opinions of the natural philosophers presented in the beginning of this treatise on the sea.
Dicit ergo primo quod illi qui dixerunt quod mare semel generatum est, vel qualitercumque posuerunt ipsius generationem, non possunt assignare causam salsedinis. Dicunt enim isti quod a principio aqua circumdabat totam terram, et sol elevavit magnam partem aquae, ex quo contingit quod magna pars terrae remansit discooperta ab aquis; et illud quod fuit residuum et nondum desiccatum a sole, factum est mare. Si ergo in multitudine aquae maris, quae secundum naturam suam deberet esse dulcis, facta est causa salsedinis propter admixtionem alicuius terrae ad aquam quae remansit, quae potuit dulce convertere in tantam salsedinem; cum, redeunte per pluvias aqua quae evaporavit, necesse sit quod aequalis multitudo aquae conservetur supra terram, ut supra dictum est; necesse est quod etiam primo, antequam sol incoeperit desiccare, mare esset salsum; vel, si prius non fuit salsum, neque posterius salsum erit, ex quo tota aqua quae elevata est, redit. Et sic non potest dici quod terra admixta facit aquam existentem nunc minoris quantitatis salsam, quod non poterat facere salsam totam, cum sit aequalis quantitatis nunc et prius. Si autem etiam a principio mare erat salsum, remanebit assignare causam salsedinis. Et etiam dicendum est quare, si a principio non ferebatur sursum aqua per evaporationem, nunc hoc accidit. 165. He says therefore first [171] that those who declared that the sea was at onetime generated, or posit its generation in any way, cannot assign a reason for its saltness. For they say that in the beginning water surrounded the entire earth and that the sun raised aloft a great portion of the water, leaving a large area of the earth no longer covered with water, and that the residue, not yet dried up by the sun, became the sea. Now, if the cause of salt in the totality of the sea's water (which according to its nature ought to be sweet), came about because of earth's mixing with the water that remained, which was able to convert the sweet into so great saltness, then, since, with the return in the form of rain of the evaporated water, there necessarily results an equal amount of water's being preserved on earth, as was said, it is necessary that even in the first place, before the sun began its drying process, that the sea be salty; or if it was not salty before, it will not be salty later, because all the evaporated water returns. Consequently, it cannot be said that mixing with earth makes the water salty because now it exists in a smaller amount, while it could not make the total amount salty — since the amount both now and before is equal. But if the sea was salty from the start, it will remain to assign a cause of its saltness. Moreover, one should state why, if water was not borne aloft by evaporation from the very beginning, this happens now.
Deinde cum dicit: at vero et quicumque terram etc., prosequitur secundam opinionem. Et dicit quod illi etiam qui dixerunt admixtionem terrae esse causam salsedinis maris, non sufficienter ostendunt quare mare est salsum. Dicunt enim quod terra habet multos sapores secundum diversas sui partes; ita quod terra quam flumina deferunt ad mare, admiscetur mari, et facit ipsum salsum. 166. Then [172 he continues with the second opinion, and says that they who declared that mixing with earth to be the cause of the sea's saltness fail to explain sufficiently why the sea is salty. For they claim that the earth has many tastes according to its various areas, so that the earth which the rivers transport to the sea mingles with the sea and makes it salty.
Sed hoc inconveniens videtur, quod mare sic fiat salsum per admixtionem terrae, et fluvii non sint salsi, qui sunt minoris quantitatis. Si ergo magna multitudo aquae maris permutatur ad salsedinem ex admixtione terrae, multo magis immutaretur aqua uniuscuiusque fluvii. Manifestum est enim quod mare est congregatio omnium fluvialium aquarum: in nullo enim differt aqua maris ab aquis fluminum, nisi per salsedinem aquae; quae non accidit in aquis fluminum, sed solum in loco in quo omnia flumina congregantur. Et hoc non videtur possibile, si sola admixtio terrae a fluminibus delatae, salsedinem causaret. But this seems unacceptable, namely, that the sea become salty through mixing with earth, while the rivers, which are smaller, are not salty. Indeed, if the vast quantity of the water of the sea is changed to salt by mixing with earth, the water of every river should, with even greater reason, be changed. For it is plain that the sea is an assemblage of all river waters — for the water of the sea differs from the water of rivers only by its saltness - something that does not occur in the waters of rivers, but only in the place where all the rivers come together. And this does not seem possible, if the sole mixing of-earth transported by the rivers were to be the cause of saltness.
Tertio ibi: similiter autem derisibile etc., improbat tertiam opinionem tribus rationibus. Quarum prima est sumpta ex hoc quod immanifeste causam salsedinis assignavit. Et dicit quod derisibile est, si quis putet aliquid planum dixisse, dicens mare esse sudorem terrae, et ob hoc esse salsum, sicut Empedocles dixit. Forte enim sufficienter dixit, si intendit metaphorice dicere, secundum modum poeticum: dicere enim aliquid per metaphoras pertinet ad poetas, et probabile est quod Empedocles, qui metrice scripsit, ut dicitur, multa metaphorice protulerit. Sed tamen sic aliquid dicere non sufficit ad cognoscendam naturam rei: quia res naturalis per similitudinem quae assumitur in metaphora, non est manifesta. Quomodo enim, cum illud quod homo potat, sit dulce, sudor exinde generatus fiet salsus? Non enim fit manifestum per metaphoram: utrum scilicet sudor remaneat salsus per separationem alicuius quod erat dulcissimum in poculo; aut efficiatur salsus per commixtionem alicuius, sicut accidit in aquis quae colantur per cinerem, quia per admixtionem cineris efficiuntur salsae vel amarae. Et eadem causa videtur esse de sapore urinae, quae est superfluitas collecta in vesica: quia huiusmodi superfluum fit amarum et salsum, cum humidum potatum sit dulce. 167. Thirdly [173], he disproves the third opinion with three arguments. The first of these is taken from the fact that it assigned a non-evident cause of the saltness. And he says that it is ridiculous for someone to think he is speaking plainly, when he says that the sea is the earth's sweat and is for that reason salty, as Empedocles said. This perhaps satisfies the demands of metaphorical utterances according to the manner of poets — for to speak in metaphors pertains to poets, and it is probable that Empedocles, who wrote in meter, so they say, uttered many things metaphorically. But such a manner of speaking is not sufficient for knowing the nature of a thing; because a natural thing is not revealed by the comparisons employed in a metaphor. For how does it come about that what a man drinks is sweet, whereas the sweat generated therefrom will be salty? The metaphor does not make it clear whether the sweat remains salty because of the separation of something that was very sweet in the drink, or by a mixing with something, as happens when water is strained through ashes, for by mixing with ashes it is made salty or bitter. And the same cause seems to be at work in the taste of urine, which is a superfluity collected in the bladder: for this residue becomes bitter and salty, although the moisture imbibed was sweet.
Si igitur ita est, quod aqua colata per calcem fit amara; et similiter etiam cum urina defertur aliqua res talis virtutis, quod possit ipsam salsam facere (nam in vasis in quibus residens conservatur urina, subsidere invenitur quaedam limositas salsa); et similiter est in sudore, quod adhaeret ei aliquid simile, cum sudor resolvitur a carnibus, quod facit ipsum salsum, tanquam si hoc humidum, quod exit a corpore per sudorem, abluat a carnibus illam superfluitatem quae facit sudorem salsum: si inquam ita est in istis tribus rebus, et metaphora de sudore est bene accepta, manifestum est quod etiam in mari erit causa salsedinis aliquid terrestre admixtum aquis. Quid autem sit quod facit salsedinem in corpore animalis, in sudore et urina, cognoscitur: quia est hypostasis alimenti, idest illud quod subsidet residuum ab eo quod attrahitur in usum alimenti nutriti. Et hoc quidem est causa salsedinis, quia non est digestum. Sed quid sit illud quod hoc modo possit facere salsedinem in mari, adhuc esset dicendum Empedocli, cum non sit manifestum. Et sic patet quod in hoc peccavit Empedocles, quod non manifeste assignavit causam. Now, if it is true that water becomes bitter because it is strained through lime, and likewise if along with urine is carried something of such virtue as to make it salty (for when urine is kept standing in chamber-pots a certain salty sediment is found to settle); and likewise with sweat, something similar adheres to it when the sweat is exuded from the flesh, which makes it salty, as though the moisture leaving the body in the form of sweat washed from the flesh a residue which makes the sweat salty; if, I say, this is so in these three cases, and if the metaphor about sweat is rightly taken, then it is plain that also in the case of the sea, the cause of saltness will be something earthy mixing with the waters. But we know the cause of salt in the body of an animal, in sweat and in urine: it is the "hypostasis of food," i.e., the subsisting residue from what is appropriated as food by anything fed. The reason why it is salty is that it has not been digested. But what it is that can in like manner produce salt in the sea Empedocles has yet to say, since this is not manifest. And so it is plain that Empedocles sinned in this: that he did not clearly indicate the cause.
Secundam rationem ponit ibi: omnino autem quomodo possibile etc.: quia, desiccata et calefacta tanta multitudine aquae, quanta a mari segregatur, tamen tota aqua maris salsa remanet; pars autem quae elevatur a terra per evaporationem, est submultiplex illius aquae quae in terra relinquitur (dicitur autem submultiplex, quae comparatur ad aliud sicut dimidium ad duplum, vel sicut subtriplum ad triplum, et sic de aliis). Unde non videtur quod aqua maris, cum sit maior pars quam aqua elevata per evaporationem, ex hoc possit fieri salsa: nam sudor et urina, quae fiunt salsa, sunt multo minora quam humiditas in corpore remanens. 168. He presents the second argument [174]; namely, that in spite of the drying up and warming of such a vast amount of water as is taken from the sea, nevertheless the whole water of the sea still remains salty. Now the portion raised away from the earth by evaporation is a submultiple of the water left on the earth (that is called "submultiple" which is to another as 1/2 is to double, or 1/3 to triple, and so forth). Hence it does not seem that the water of the sea, since it is a greater amount than the water borne up by evaporation can become salty from this, for sweat and urine, both of which are salty, are much less in volume than the moisture remaining in the body.
Tertiam rationem ponit ibi: adhuc autem propter quid et cetera. Et dicit quod quaerendum est ab Empedocle quare nunc terra, postquam desiccata est a sole in aliqua parte sui, sive maiori sive minori, non sudat, ita quod sudor eius appareat amarus: si enim hoc fuit a principio, quod terra sudaret humorem amarum, et nunc deberet fieri. Sed hoc non videtur nunc accidere: videmus enim quod terra, cum est humida, siccari potest, et postquam est sicca, non patitur aliquid tale, scilicet ut sudet. Neque igitur possibile fuit quod in prima generatione mundi, terra existens humida, quia circumdata aquis, sudaret per exsiccationem: sed magis verisimilis est opinio illorum qui dixerunt quod mare non est sudor terrae, sed aqua relicta post exsiccationem alicuius partis terrae: quod enim terra humida existens sudet, videtur impossibile. 169. He presents the third argument [175], and says that Empedocles must be asked why it is that after being dried out in various small or large areas by the sun, the earth does not now sweat with a sweat that seems bitter: for if it was true in the beginning that the earth sweated a bitter moistness, it should be doing so even now. But this is not seen to be happening now: for we see that the earth, when moist, can be dried out, and after it is dried out, it does not undergo anything like this, i.e., sweating. Neither, therefore, was it possible in the primal generation of the world, when the earth was moist (because it was covered with water), for it to sweat through being dried out. Closer to the truth is the theory upheld by those who said that the sea is not the sweat of the earth but is water left after some portion of the earth did dry out. However, that the earth should sweat when moist, seems impossible.
Et sic ultimo concludit quod causae quae adducuntur de salsedine maris, videntur effugere rationem. And so he finally concludes that the causes alleged for the saltness of the sea are seen to elude reason.

Lecture 6
Cause of the sea's saltness according to Aristotle
Chapter 3 cont.
ἡμεῖς δὲ λέγωμεν ἀρχὴν λαβόντες τὴν αὐτὴν ἣν καὶ πρότερον ἐπειδὴ γὰρ κεῖται διπλῆν εἶναι τὴν ἀναθυμίασιν, τὴν μὲν ὑγρὰν τὴν δὲ ξηράν, δῆλον ὅτι ταύτην οἰητέον ἀρχὴν εἶναι τῶν τοιούτων. καὶ δὴ καὶ περὶ οὗ ἀπορῆσαι πρότερον ἀναγκαῖον, πότερον καὶ ἡ θάλαττα ἀεὶ διαμένει τῶν αὐτῶν οὖσα μορίων ἀριθμῷ ἢ τῷ εἴδει καὶ τῷ ποσῷ μεταβαλλόντων ἀεὶ τῶν μερῶν, καθάπερ ἀὴρ καὶ τὸ πότιμον ὕδωρ καὶ πῦρ (ἀεὶ γὰρ ἄλλο καὶ ἄλλο γίγνεται τούτων ἕκαστον, τὸ δ' εἶδος τοῦ πλήθους ἑκάστου τούτων μένει, καθάπερ τὸ τῶν ῥεόντων ὑδάτων καὶ τὸ τῆς φλογὸς ῥεῦμα) φανερὸν δὴ καὶ τοῦτο καὶ πιθανόν, ὡς ἀδύνατον μὴ τὸν αὐτὸν εἶναι περὶ πάντων τούτων λόγον, καὶ διαφέρειν ταχυτῆτι καὶ (358a.) βραδυτῆτι τῆς μεταβολῆς, ἐπὶ πάντων τε φθορὰν εἶναι καὶ γένεσιν, ταύτην μέντοι τεταγμένως συμβαίνειν πᾶσιν αὐτοῖς. 176 Since all the attempts to account for the saltness of the sea seem unsuccessful let us explain it by the help of the principle we have used already. Since we recognize two kinds of evaporation, one moist, the other dry, it is clear that the latter must be recognized as the source of phenomena like those we are concerned with. But there is a question which we must discuss first. Does the sea always remain numerically one and consisting of the same parts, or is it, too, one in form and volume while its parts are in continual change, like air and sweet water and fire? All of these are in a constant state of change, but the form and the quantity of each of them are fixed, just as they are in the case of a flowing river or a burning flame. The answer is clear, and there is no doubt that the same account holds good of all these things alike. They differ in that some of them change more rapidly or more slowly than others; and they all are involved in a process of perishing and becoming which yet affects them all in a regular course.
τούτων δ' οὕτως ἐχόντων, πειρατέον ἀποδοῦναι τὴν αἰτίαν καὶ περὶ τῆς ἁλμυρότητος. φανερὸν δὴ διὰ πολλῶν σημείων ὅτι γίγνεται τοιοῦτος ὁ χυμὸς διὰ σύμμειξίν τινος. ἔν τε γὰρ τοῖς σώμασι τὸ ἀπεπτότατον ἁλμυρὸν καὶ πικρόν, ὥσπερ καὶ πρότερον εἴπομεν ἀπεπτότατον γὰρ τὸ περίττωμα τῆς ὑγρᾶς τροφῆς τοιαύτη δὲ πᾶσα μὲν ἡ ὑπόστασις, μάλιστα δὲ ἡ εἰς τὴν κύστιν (σημεῖον δ' ὅτι λεπτοτάτη ἐστίν τὰ δὲ πεττόμενα πάντα συνίστασθαι πέφυκεν) ἔπειτα ἱδρώς [ἀεί] ἐν οἷς τὸ αὐτὸ σῶμα συνεκκρίνεται, ὃ ποιεῖ τὸν χυμὸν τοῦτον. ὁμοίως δὲ καὶ ἐν τοῖς καομένοις οὗ γὰρ ἂν μὴ κρατήσῃ τὸ θερμόν, ἐν μὲν τοῖς σώμασι γίγνεται περίττωσις, ἐν δὲ τοῖς καομένοις τέφρα. 177 This being so we must go on to try to explain why the sea is salt. There are many facts which make it clear that this taste is due to the admixture of something. First, in animal bodies what is least digested, the residue of liquid food, is salt and bitter, as we said before. All animal excreta are undigested, but especially that which gathers in the bladder (its extreme lightness proves this; for everything that is digested is condensed), and also sweat; in these then is excreted (along with other matter) an identical substance to which this flavour is due. The case of things burnt is analogous. What heat fails to assimilate becomes the excrementary residue in animal bodies, and, in things burnt, ashes.
διὸ καὶ τὴν θάλαττάν τινες ἐκ κατακεκαυμένης φασὶ γενέσθαι γῆς. ὃ οὕτω μὲν εἰπεῖν ἄτοπον, τὸ μέντοι ἐκ τοιαύτης ἀληθές ὥσπερ γὰρ καὶ ἐν τοῖς εἰρημένοις, οὕτω καὶ ἐν τῷ ὅλῳ ἔκ τε τῶν φυομένων καὶ γιγνομένων κατὰ φύσιν ἀεὶ δεῖ νοεῖν, ὥσπερ ἐκ πεπυρωμένων τὸ λειπόμενον τοιαύτην εἶναι γῆν, καὶ δὴ καὶ τὴν ἐν τῇ ξηρᾷ ἀναθυμίασιν πᾶσαν αὕτη γὰρ καὶ παρέχεται τὸ πολὺ τοῦτο πλῆθος. μεμειγμένης δ' οὔσης, ὥσπερ εἴπομεν, τῆς τε ἀτμιδώδους ἀναθυμιάσεως καὶ τῆς ξηρᾶς, ὅταν συνιστῆται εἰς νέφη καὶ ὕδωρ, ἀναγκαῖον ἐμπεριλαμβάνεσθαί τι πλῆθος ἀεὶ ταύτης τῆς δυνάμεως, καὶ συγκαταφέρεσθαι πάλιν ὕοντος, καὶ τοῦτ' ἀεὶ γίγνεσθαι κατά τινα τάξιν, ὡς ἐνδέχεται μετέχειν τὰ ἐνταῦθα τάξεως. ὅθεν μὲν οὖν ἡ γένεσις ἔνεστιν τοῦ ἁλμυροῦ ἐν τῷ ὕδατι, εἴρηται. 178 That is why some people say that it was burnt earth that made the sea salt. To say that it was burnt earth is absurd; but to say that it was something like burnt earth is true. We must suppose that just as in the cases we have described, so in the world as a whole, everything that grows and is naturally generated always leaves an undigested residue, like that of things burnt, consisting of this sort of earth. All the earthy stuff in the dry exhalation is of this nature, and it is the dry exhalation which accounts for its great quantity. Now since, as we have said, the moist and the dry evaporations are mixed, some quantity of this stuff must always be included in the clouds and the water that are formed by condensation, and must redescend to the earth in rain. This process must always go on with such regularity as the sublunary world admits of, and it is the answer to the question how the sea comes to be salt.
καὶ διὰ τοῦτο τά τε νότια ὕδατα πλατύτερα καὶ τὰ πρῶτα τῶν μετοπωρινῶν ὅ τε γὰρ νότος καὶ τῷ μεγέθει καὶ τῷ πνεύματι ἀλεεινότατος ἄνεμός ἐστιν, καὶ πνεῖ ἀπὸ τόπων ξηρῶν καὶ θερμῶν, ὥστε μετ' ὀλίγης ἀτμίδος. διὸ καὶ θερμός ἐστιν εἰ γὰρ καὶ μὴ τοιοῦτος, ἀλλ' ὅθεν ἄρχεται πνεῖν ψυχρός, οὐδὲν ἧττον προϊὼν διὰ τὸ συμπεριλαμβάνειν πολλὴν ἀναθυμίασιν ξηρὰν ἐκ τῶν σύνεγγυς τόπων θερμός ἐστιν ὁ δὲ βορέας ἅτε ἀφ' ὑγρῶν τόπων ἀτμιδώδης διὸ (358b.) ψυχρός τῷ δ' ἀπωθεῖν αἴθριος ἐνταῦθα, ἐν δὲ τοῖς ἐναντίοις ὑδατώδης. ὁμοίως δὲ καὶ ὁ νότος αἴθριος τοῖς περὶ τὴν Λιβύην. πολὺ οὖν ἐν τῷ καταφερομένῳ ὕδατι συμβάλλεται τοιοῦτον, καὶ τοῦ μετοπώρου πλατέα τὰ ὕδατα ἀνάγκη γὰρ τὰ βαρύτατα πρῶτα φέρεσθαι. ὥστ' ἐν ὅσοις ἔνεστι τῆς τοιαύτης γῆς πλῆθος, ῥέπει τάχιστα κάτω ταῦτα. καὶ θερμή γε ἡ θάλαττα διὰ τοῦτό ἐστιν πάντα γὰρ ὅσα πεπύρωται, ἔχει δυνάμει θερμότητα ἐν αὑτοῖς. ὁρᾶν δ' ἔξεστι καὶ τὴν κονίαν καὶ τὴν τέφραν καὶ τὴν ὑπόστασιν τῶν ζῴων καὶ τὴν ξηρὰν καὶ τὴν ὑγράν καὶ τῶν θερμοτάτων γε κατὰ τὴν κοιλίαν ζῴων συμβαίνει θερμοτάτην εἶναι τὴν ὑπόστασιν. 179 It also explains why rain that comes from the south, and the first rains of autumn, are brackish. The south is the warmest of winds and it blows from dry and hot regions. Hence it carries little moist vapour and that is why it is hot. (It makes no difference even if this is not its true character and it is originally a cold wind, for it becomes warm on its way by incorporating with itself a great quantity of dry evaporation from the places it passes over.) The north wind, on the other hand, coming from moist regions, is full of vapour and therefore cold. It is dry in our part of the world because it drives the clouds away before it, but in the south it is rainy; just as the south is a dry wind in Libya. So the south wind charges the rain that falls with a great quantity of this stuff. Autumn rain is brackish because the heaviest water must fall first; so that that which contains the greatest quantity of this kind of earth descends quickest. This, too, is why the sea is warm. Everything that has been exposed to fire contains heat potentially, as we see in the case of lye and ashes and the dry and liquid excreta of animals. Indeed those animals which are hottest in the belly have the hottest excreta.
γίγνεται μὲν οὖν ἀεί τε πλατυτέρα διὰ ταύτην τὴν αἰτίαν, ἀνάγεται δ' ἀεί τι μέρος αὐτῆς μετὰ τοῦ γλυκέος (ἀλλ' ἔλαττον τοσούτῳ ὅσῳ καὶ ἐν τῷ ὑομένῳ τὸ ἁλμυρὸν καὶ πλατὺ τοῦ γλυκέος ἔλαττον διόπερ ἰσάζει ὡς ἐπίπαν εἰπεῖν). 180 The action of this cause is continually making the sea more salt, but some part of its saltness is always being drawn up with the sweet water. This is less than the sweet water in the same ratio in which the salt and brackish element in rain is less than the sweet, and so the saltness of the sea remains constant on the whole.
ὅτι δὲ γίγνεται ἀτμίζουσα πότιμος καὶ οὐκ εἰς θάλατταν συγκρίνεται τὸ ἀτμίζον, ὅταν συνιστῆται πάλιν, πεπειραμένοι λέγωμεν. πάσχει δὲ καὶ τἆλλα ταὐτό καὶ γὰρ οἶνος καὶ πάντες οἱ χυμοί, ὅσοι ἂν ἀτμίσαντες πάλιν εἰς ὑγρὸν συστῶσιν, ὕδωρ γίγνονται πάθη γὰρ τἆλλα διά τινα σύμμειξιν τοῦ ὕδατός ἐστιν, καὶ οἷον ἄν τι ᾖ τὸ συμμειχθέν, τοιοῦτον ποιεῖ τὸν χυμόν. ἀλλὰ περὶ μὲν τούτων ἐν ἄλλοις καιροῖς οἰκειοτέροις ποιητέον τὴν σκέψιν. 181 Salt water when it turns into vapour becomes sweet, and the vapour does not form salt water when it condenses again. This I know by experiment. The same thing is true in every case of the kind: wine and all fluids that evaporate and condense back into a liquid state become water. They all are water modified by a certain admixture, the nature of which determines their flavour. But this subject must be considered on another more suitable occasion.
νῦν δὲ τοσοῦτον λέγωμεν, ὅτι τῆς θαλάττης ὑπαρχούσης αἰεί τι ἀνάγεται καὶ γίγνεται πότιμον καὶ ἄνωθεν ἐν τῷ ὑομένῳ κατέρχεται ἄλλο γεγενημένον, οὐ τὸ ἀναχθέν καὶ διὰ βάρος ὑφίσταται τῷ ποτίμῳ. καὶ διὰ τοῦτο οὔτ' ἐπιλείπει, ὥσπερ οἱ ποταμοί, ἀλλ' ἢ τοῖς τόποις (τοῦτο δ' ἐπ' ἀμφοτέρων ἀνάγκη συμβαίνειν ὁμοίως), οὔτε ἀεὶ τὰ αὐτὰ μέρη διαμένει, οὔτε γῆς οὔτε θαλάττης, ἀλλ' ἢ μόνον ὁ πᾶς ὄγκος. καὶ γὰρ καὶ περὶ γῆς ὁμοίως δεῖ ὑπολαβεῖν τὸ μὲν γὰρ ἀνέρχεται, τὸ δὲ πάλιν συγκαταβαίνει, καὶ τοὺς τόπους μεταβάλλει τά τ' ἐπιπολάζοντα καὶ τὰ κατιόντα πάλιν. 182 For the present let us say this. The sea is there and some of it is continually being drawn up and becoming sweet; this returns from above with the rain. But it is now different from what it was when it was drawn up, and its weight makes it sink below the sweet water. This process prevents the sea, as it does rivers, from drying up except from local causes (this must happen to sea and rivers alike). On the other hand the parts neither of the earth nor of the sea remain constant but only their whole bulk. For the same thing is true of the earth as of the sea: some of it is carried up and some comes down with the rain, and both that which remains on the surface and that which comes down again change their situations.
ὅτι δ' ἐστὶν ἐν μείξει τινὸς τὸ ἁλμυρόν, δῆλον οὐ μόνον ἐκ τῶν εἰρημένων, ἀλλὰ καὶ ἐάν τις ἀγγεῖον (359a.) πλάσας θῇ κήρινον εἰς τὴν θάλατταν, περιδήσας τὸ στόμα τοιούτοις ὥστε μὴ παρεγχεῖσθαι τῆς θαλάττης τὸ γὰρ εἰσιὸν διὰ τῶν τοίχων τῶν κηρίνων γίγνεται πότιμον ὕδωρ ὥσπερ γὰρ δι' ἠθμοῦ τὸ γεῶδες ἀποκρίνεται καὶ τὸ ποιοῦν τὴν ἁλμυρότητα διὰ τὴν σύμμειξιν. τοῦτο γὰρ αἴτιον καὶ τοῦ βάρους (πλέον γὰρ ἕλκει τὸ ἁλμυρὸν ἢ τὸ πότιμον) καὶ τοῦ πάχους καὶ γὰρ τὸ πάχος διαφέρει τοσοῦτον ὥστε τὰ πλοῖα ἀπὸ τοῦ αὐτοῦ τῶν ἀγωγίμων βάρους ἐν μὲν τοῖς ποταμοῖς ὀλίγου καταδύνειν, ἐν δὲ τῇ θαλάττῃ μετρίως ἔχειν καὶ πλευστικῶς διόπερ ἔνιοι τῶν ἐν τοῖς ποταμοῖς γεμιζόντων διὰ ταύτην τὴν ἄγνοιαν ἐζημιώθησαν. τεκμήριον δὲ τοῦ μειγνυμένου τὸ παχύτερον εἶναι τὸν ὄγκον ἐὰν γάρ τις ὕδωρ ἁλμυρὸν ποιήσῃ σφόδρα μείξας ἅλας, ἐπιπλέουσι τὰ ᾠά, κἂν ᾖ πλήρη σχεδὸν γὰρ ὥσπερ πηλὸς γίγνεται τοσοῦτον ἔχει σωματῶδες πλῆθος ἡ θάλαττα. ταὐτὸ δὲ τοῦτο δρῶσι καὶ περὶ τὰς ταριχείας. εἰ δ' ἔστιν ὥσπερ μυθολογοῦσί τινες ἐν Παλαιστίνῃ τοιαύτη λίμνη, εἰς ἣν ἐάν τις ἐμβάλῃ συνδήσας ἄνθρωπον ἢ ὑποζύγιον ἐπιπλεῖν καὶ οὐ καταδύεσθαι κατὰ τοῦ ὕδατος, μαρτύριον ἂν εἴη τι τοῖς εἰρημένοις λέγουσι γὰρ πικρὰν οὕτως εἶναι τὴν λίμνην καὶ ἁλμυρὰν ὥστε μηδένα ἰχθὺν ἐγγίγνεσθαι, τὰ δὲ ἱμάτια ῥύπτειν, ἐάν τις διασείσῃ βρέξας. ἔστι δὲ καὶ τὰ τοιαῦτα σημεῖα πάντα τῶν εἰρημένων, ὅτι τὸ ἁλμυρὸν ποιεῖ σῶμά τι, καὶ γεῶδές ἐστιν τὸ ἐνυπάρχον ἔν τε γὰρ τῇ Χαονίᾳ κρήνη τίς ἐστιν ὕδατος πλατυτέρου, ἀπορρεῖ δ' αὕτη εἰς ποταμὸν πλησίον γλυκὺν μέν, ἰχθῦς δ' οὐκ ἔχοντα εἵλοντο γὰρ δή, ὡς οἱ ἐκεῖ μυθολογοῦσιν, ἐξουσίας δοθείσης ὑπὸ τοῦ Ἡρακλέους, ὅτ' ἦλθεν ἄγων ἐκ τῆς Ἐρυθείας τὰς βοῦς, ἅλας ἀντὶ τῶν ἰχθύων, οἳ γίγνονται αὐτοῖς ἐκ τῆς κρήνης τούτου γὰρ τοῦ ὕδατος ἀφέψοντές τι μέρος τιθέασι, καὶ γίγνεται ψυχθέν, ὅταν ἀπατμίσῃ τὸ ὑγρὸν ἅμα τῷ θερμῷ, ἅλες, οὐ χονδροὶ ἀλλὰ χαῦνοι καὶ λεπτοὶ ὥσπερ χιών. εἰσίν τε τήν τε δύναμιν ἀσθενέστεροι τῶν ἄλλων καὶ πλείους ἡδύνουσιν ἐμβληθέντες, καὶ τὴν χροιὰν οὐχ ὁμοίως λευκοί. τοιοῦτον δ' ἕτερον γίγνεται καὶ ἐν Ὀμβρικοῖς (359b.) ἔστι γάρ τις τόπος ἐν ᾧ πεφύκασι κάλαμοι καὶ σχοῖνος τούτων κατακάουσι, καὶ τὴν τέφραν ἐμβάλλοντες εἰς ὕδωρ ἀφέψουσιν ὅταν δὲ λίπωσί τι μέρος τοῦ ὕδατος, τοῦτο ψυχθὲν ἁλῶν γίγνεται πλῆθος. ὅσα δ' ἐστὶν ἁλμυρὰ ῥεύματα ποταμῶν ἢ κρηνῶν, τὰ πλεῖστα θερμά ποτε εἶναι δεῖ νομίζειν, εἶτα τὴν μὲν ἀρχὴν ἀπεσβέσθαι τοῦ πυρός, δι' ἧς δὲ διηθοῦνται γῆς, ἔτι μένειν οὖσαν οἷον κονίαν καὶ τέφραν. εἰσὶ δὲ πολλαχοῦ καὶ κρῆναι καὶ ῥεύματα ποταμῶν παντοδαποὺς ἔχοντα χυμούς, ὧν πάντων αἰτιατέον τὴν ἐνοῦσαν ἢ ἐγγιγνομένην δύναμιν πυρός καομένη γὰρ ἡ γῆ τῷ μᾶλλον καὶ ἧττον παντοδαπὰς λαμβάνει μορφὰς καὶ χρόας χυμῶν στυπτηρίας γὰρ καὶ κονίας καὶ τῶν ἄλλων τῶν τοιούτων γίγνεται πλήρης δυνάμεων, δι' ὧν τὰ ἠθούμενα ὕδατα ὄντα γλυκέα μεταβάλλει, καὶ τὰ μὲν ὀξέα γίγνεται, καθάπερ ἐν τῇ Σικάνῃ τῆς Σικελίας ἐκεῖ γὰρ ὀξάλμη γίγνεται, καὶ χρῶνται καθάπερ ὄξει πρὸς ἔνια τῶν ἐδεσμάτων αὐτῷ. ἔστι δὲ καὶ περὶ Λύγκον κρήνη τις ὕδατος ὀξέος, περὶ δὲ τὴν Σκυθικὴν πικρά τὸ δ' ἀπορρέον αὐτῆς τὸν ποταμὸν εἰς ὃν εἰσβάλλει ποιεῖ πικρὸν ὅλον. αἱ δὲ διαφοραὶ τούτων ἐκεῖθεν δῆλαι, ποῖοι χυμοὶ ἐκ ποίων γίγνονται κράσεων εἴρηται δὲ περὶ αὐτῶν χωρὶς ἐν ἄλλοις. 183 There is more evidence to prove that saltness is due to the admixture of some substance, besides that which we have adduced. Make a vessel of wax and put it in the sea, fastening its mouth in such a way as to prevent any water getting in. Then the water that percolates through the wax sides of the vessel is sweet, the earthy stuff, the admixture of which makes the water salt, being separated off as it were by a filter. It is this stuff which make salt water heavy (it weighs more than fresh water) and thick. The difference in consistency is such that ships with the same cargo very nearly sink in a river when they are quite fit to navigate in the sea. This circumstance has before now caused loss to shippers freighting their ships in a river. That the thicker consistency is due to an admixture of something is proved by the fact that if you make strong brine by the admixture of salt, eggs, even when they are full, float in it. It almost becomes like mud; such a quantity of earthy matter is there in the sea. The same thing is done in salting fish. Again if, as is fabled, there is a lake in Palestine, such that if you bind a man or beast and throw it in it floats and does not sink, this would bear out what we have said. They say that this lake is so bitter and salt that no fish live in it and that if you soak clothes in it and shake them it cleans them. The following facts all of them support our theory that it is some earthy stuff in the water which makes it salt. In Chaonia there is a spring of brackish water that flows into a neighbouring river which is sweet but contains no fish. The local story is that when Heracles came from Erytheia driving the oxen and gave the inhabitants the choice, they chose salt in preference to fish. They get the salt from the spring. They boil off some of the water and let the rest stand; when it has cooled and the heat and moisture have evaporated together it gives them salt, not in lumps but loose and light like snow. It is weaker than ordinary salt and added freely gives a sweet taste, and it is not as white as salt generally is. Another instance of this is found in Umbria. There is a place there where reeds and rushes grow. They burn some of these, put the ashes into water and boil it off. When a little water is left and has cooled it gives a quantity of salt. Most salt rivers and springs must once have been hot. Then the original fire in them was extinguished but the earth through which they percolate preserves the character of lye or ashes. Springs and rivers with all kinds of flavours are found in many places. These flavours must in every case be due to the fire that is or was in them, for if you expose earth to different degrees of heat it assumes various kinds and shades of flavour. It becomes full of alum and lye and other things of the kind, and the fresh water percolates through these and changes its character. Sometimes it becomes acid as in Sicania, a part of Sicily. There they get a salt and acid water which they use as vinegar to season some of their dishes. In the neighbourhood of Lyncus, too, there is a spring of acid water, and in Scythia a bitter spring. The water from this makes the whole of the river into which it flows bitter. These differences are explained by a knowledge of the particular mixtures that determine different savours. But these have been explained in another treatise.
περὶ μὲν οὖν ὕδατος καὶ θαλάττης, δι' ἃς αἰτίας αἰεί τε συνεχῶς εἰσι καὶ πῶς μεταβάλλουσι καὶ τίς ἡ φύσις αὐτῶν, ἔτι δ' ὅσα πάθη κατὰ φύσιν αὐτοῖς συμβαίνει ποιεῖν ἢ πάσχειν, εἴρηται σχεδὸν ἡμῖν περὶ τῶν πλείστων. 184 We have now given an account of waters and the sea, why they persist, how they change, what their nature is, and have explained most of their natural operations and affections.
Reprobatis opinionibus de salsedine maris, hic ponit opinionem propriam. Et circa hoc tria facit: 170. Having rejected these theories about the salt of the sea, he now presents his own opinion. About this he does three things:

primo praemittit quaedam quae sunt necessaria ad propositum manifestandum;

secundo assignat causam salsedinis maris, ibi: his autem sic se habentibus etc.;

tertio manifestat quod dixerat per signa, ibi: quod autem est in commixtione et cetera.

First, he prefaces some things needed for manifesting the proposition;

Secondly, he assigns the cause of the sea's saltness, at 171;

Thirdly, he manifests what he had said through signs, at 177.

Circa primum duo facit. Quorum primum resumit ex praedictis, videlicet quod est duplex exhalatio, una humida et alia sicca: et hanc putandum est esse principium horum, scilicet salsedinis maris. In regard to the first he does two things [176]. The first item he repeats from the foregoing is that exhalations are of two kinds: one is moist and the other dry; and this must be regarded as the source of these, i.e., of the sea's saltness.
Secundum est, quod movet dubitationem, de qua oportet primo videre veritatem, antequam propositum manifestet. Et est ista quaestio: utrum partes maris semper maneant eaedem numero; aut permutentur secundum numerum, et maneant eaedem secundum quantitatem, sicut accidit in aere et in aqua potabili fluminum et in igne. In his enim omnibus partes fiunt aliae et aliae numero, sed species vel forma multitudinis harum partium manet eadem: et hoc apparet maxime in aquis fluentibus et in fluxu flammae, quae per successionem fumi semper innovatur, ut supra dictum est, et tamen flamma semper manet eadem in numero. Unde probabile est non esse eandem rationem in his omnibus: nam ad minus differentia est secundum velocitatem permutationis; manifestum est enim quod citius permutantur partes aquae fluentis, quam partes terrae. In omnibus tamen est generatio et corruptio secundum partes per aliquem ordinem. Secondly, he raises a problem whose true solution must be seen before the proposition is manifested. The problem is this: do the parts of the sea always remain numerically the same or are they changed in number while remaining the same according to quantity, as happens in air and in the drinkable water of rivers and in fire? For in all these the parts become other and other in number, but the species or form of the aggregate of these parts remains the same; and this is especially evident in flowing waters and in a burning flame, which is forever being renewed by successively new fumes, as was said above, and yet the flame always remains the same numerical one. Hence it is probable that all these cases are not exactly the same, for there is at least a difference so far as the rapidity of change is concerned: for it is plain that the parts of a flowing stream are exchanged more rapidly than the parts of the earth. Yet in all these cases there is a generation and corruption according to parts, following a certain order.
Deinde cum dicit: his autem sic se habentibus etc., assignat causam salsedinis maris. Et circa hoc duo facit: 171. Then [177] he assigns the cause of the sea's salt. About this he does two things:

primo ostendit in generali unde causetur sapor salsus;

secundo unde causetur salsedo in mari, ibi: propter quod et mare et cetera.

First, he shows in general from what source a salty savor is produced;

Secondly, from what source is derived the saltness of the sea, at 172.

Dicit ergo primo quod, cum praemissa sic se habeant ut dictum est, oportet reddere causam de salsedine maris. Manifestum est autem per multa signa quod sapor salsus causatur ex admixtione alicuius. Videmus enim quod in corporibus animalium illud quod est indigestissimum, est salsum et amarum: hoc autem maxime est superfluitas alimenti, et maxime quae congregatur in vesica. Et quod haec sit indigestissima, significatur per hoc quod est subtilissima inter omnes superfluitates; omnia autem digesta videntur inspissata esse a calore. Et sicut est de urina, ita est de sudore: similiter enim cum sudore segregatur aliquid indigestum, quod facit talem saporem. Similiter est in adustis: quia illud quod est residuum ab actione caloris, inquantum calor non potest vincere, in corporibus animalium fit superfluitas, in adustis autem fit cinis, per cuius admixtionem aqua etiam redditur salsa et amara. He says therefore first [177] that, since the above are as described, there is need to set forth the cause of the sea's saltness. For it is plain by many signs that the salty taste is caused by an admixture of something. For we see that, in the bodies of animals, what is most undigested is salty and bitter: this is especially the residue of food, and more especially the residue collected in the bladder. That this is least digested is indicated by the fact that it is the most refined of all the residues, whereas all digested things are seen to be thickened by heat. And as with urine, so with sweat: for likewise with sweat, something undigested is separated which gives it this taste. So too with burnt things: because whatever is left after the action of the heat, that the heat cannot overcome, becomes a residue in the bodies of animals, and ash in burned objects, which, if mixed with water, makes it salty and bitter.
Deinde cum dicit: propter quod et mare etc., assignat specialiter causam salsedinis maris. Et circa hoc tria facit: 172. Then [178] he assigns the specific cause of the sea's saltness. About this he does three things:

primo facit quod dictum est;

secundo hoc manifestat per quaedam signa, ibi: et propter hoc Australes etc.;

tertio excludit quasdam obiectiones, ibi: fit igitur semper alterum et cetera.

First, he does what is said;

Secondly, he manifests this through certain signs, at 173;

Thirdly, he excludes some objections, at 174.

Dicit ergo primo, quod propter hoc quod sapor salsus et amarus invenitur causari ex admixtione alicuius indigesti vel adusti, quidam dixerunt quod mare erat factum ex terra adusta. Quod quidem inconveniens est, si intelligatur secundum quod dicitur: sed si intelligatur dictum per similitudinem, ut scilicet salsedo in mari causetur per admixtionem alicuius quod est simile cum terra adusta, sic verum est. Sicut enim contingit in praedictis, scilicet urina, sudore et cinere, sic oportet intelligere et in tota terra: sicuti enim ex ignitis relinquitur aliquid quod non potuit ignis dissolvere, ita oportet intelligere relinqui circa terram ab actione caloris aliquid simile cineri relicto ab actione ignis. Et huius similitudinem habet exhalatio quae fit ex arida, cuius multitudinem terra exhibet. Huiusmodi igitur exhalatio sicca cum admiscetur vaporosae exhalationi, quae condensatur in nubes et pluviam, necesse est quod semper in illa exhalatione humida contineatur aliquid virtutis huius, scilicet exhalationis siccae; et sic simul utrumque commixtum fertur deorsum, aqua pluente. Hoc autem fit secundum quendam ordinem semper, ut scilicet exhalationes commixtae eleventur, et iterum cadant per pluviam. Dico autem hoc secundum ordinem fieri, secundum quod ea quae hic inferius fiunt, possunt participare ordinem: non enim sic pure participant ordinem ut sint semper eodem modo, sicut est de corporibus caelestibus, sed accidunt ut frequenter. Et sic concludit quod dictum est unde fiat generatio salsi in aqua maris. He says therefore first [178] that since a salty and bitter taste is found to be caused by the admixture of something undigested or burnt, some have said that the sea was formed out of charred earth. But this is unacceptable if taken in a literal sense; taken as a metaphor, however, namely, in the sense that the saltiness in the sea is caused by a mixing with something akin to charred earth, then it is true. For just as it occurs in the aforesaid, namely, in urine, sweat and ashes, so it must be understood even in regard to the earth as a whole: just as burning objects leave a residue of certain items that the fire was unable to dissolve, so too we must understand something to be left with respect to the earth by the action of heat, similar to the ash left by the action of fire. An example of this is the exhalation arising out of dry land, the magnitude of which the earth shows. Now when a dry exhalation of this sort mixes with the moist exhalation that is condensed into clouds and rain, it is necessary that in that moist exhalation there be contained something of the power of that dry exhalation; as a consequence, both mixed together re-descend when it rains. But this always occurs in a definite order: the mingled exhalations are borne aloft and re-descend in the form of rain. I say that this takes place in a definite order, i.e., to the extent that things occurring in the lower regions can participate in order: for they do not participate in order so perfectly as to occur always in the same way as do the heavenly bodies, but so as to occur for the most part. And thus he concludes that this sets forth whence there is generation of salt in the water of the sea.
Deinde cum dicit: et propter hoc Australes etc., manifestat quae dixerat per quaedam signa. Et dicit quod propter hoc quod exhalatio sicca admiscetur evaporationi humidae, aquae Australes et aquae quae primo cadunt in autumno, sunt latiores, idest graviores et magis ad salsedinem tendentes. 173. Then [179] he manifests what he had said through certain signs. And he says that because the dry exhalation mixes with the moist evaporation, southern waters and the first waters to fall in autumn are brackish, i.e., heaver and more on the salty side.
Et primo manifestat hoc de aquis Australibus, idest quae cadunt Austro flante. Auster enim et flatu et magnitudine est valde calidus: flat enim a locis calidis et siccis, in quibus est parum de vapore humido, et ideo est calidus. Sed quia posset aliquis dicere quod flat a locis frigidis, scilicet a polo Antarctico, quem oportet esse frigidum propter distantiam a sole, ideo subiungit quod, etsi hoc dicatur quod non flat a locis calidis sed a frigidis, tamen oportet quod transeat ad nos per loca calida et sicca, ex locis propinquis; et ideo est calidus. Sed Boreas, qui venit ad nos immediate ex locis frigidis, congregat multos vapores humidos et frigidos; et propter hoc est frigidus. Sed tamen nobis est serenus, quia impellit huiusmodi vapores ad partem oppositam: sed in locis et regionibus meridionalibus est aquosus, quia illuc impellit vapores. Et e converso Auster est serenus illis qui habitant in meridionalibus, scilicet circa Lybiam, cum nobis sit pluviosus. Sic igitur quia Auster colligit multum de exhalatione sicca, talis ventus confert multum ad hoc quod descendat aqua salsa. Et sic patet ratio unius eorum quae dicta sunt, scilicet quare aquae Australes sunt latiores. First he explains this with respect to "southern" waters, i.e., which fall with the south wind blowing. For the south wind in its blowing and in its size is very warm: for it blows from regions that are hot and dry and have little moisture — that is why it is a hot wind. But because one could say that it blows from a cold region, namely, from the antarctic pole, which must be cold on account of its distance from the sun, he adds that, even supposing that it blows, not from the hot, but from the cold places, nevertheless it must travel toward us through regions close to us that are hot and dry, as to proximate regions: hence it is hot. But the north wind, which comes to us directly from cold regions, collects many moist and cold vapors along with it: therefore, it is a cold wind. Yet for us it brings clear weather, because it drives these vapors in the opposite direction; but in places and regions in the south it is a wet wind, because that is where it drives the vapors. Conversely, a south wind is clear for those who live in the south, namely, around Libya, but for us it is rainy. And so, because a south wind collects a large quantity of dry exhalation, such a wind contributes a great deal to the falling of water that is salty. Thus is made plain the reason for one of the statements, namely, why rains from the south are brackish.
Sed quia hoc etiam dixerat de primis aquis autumnalibus, assignat etiam huius causam: quia scilicet necesse est quod ea quae sunt gravissima in vaporibus elevatis, prius deorsum ferantur; gravissima autem sunt in quibus est plurimum de terrestri; et ideo aquae primo cadentes in autumno post aestatem, sunt latiores, valde plurimum de terrestri habentes. But because the same was said of the first rains of autumn, he also assign s a cause for this: it is necessary that the heaviest constituents of the vapors carried aloft descend first; but the heaviest are those containing the most earth; and that is why the first waters to fall in autumn after the summer are brackish and have a great deal of what is earthy.
Aliud etiam signum assignat praedictae rationi assignatae de salsedinis causa: quia scilicet propter hoc mare est calidum, et regiones propinquae mari sunt calidiores, propter abundantiam scilicet praedictae exhalationis mixtae aquae maris. Quaecumque enim fuerint ignita, etiam post extinctionem videntur habere virtutem caloris in seipsis, ut patet in cinere et calce et superfluitate animalium habentium calidos ventres. Et huius ratio est, quia in huiusmodi manet virtus caloris alterantis cum exhalatione sicca. Unde, cum exhalationem siccam resolutam a terra desiccata, dixerit esse causam salsedinis maris, consequens est ut etiam in mari caliditas ex hoc abundet. He gives another sign in support of the reason assigned as the cause of saltness, namely, that the reason why the sea is warm and the regions near the sea are comparatively warmer is due to the abundance of the above-mentioned exhalation mixed with the water of the sea. For things previously afire are seen to possess within themselves the virtue of heat even after the fire has gone out: this is plain in ashes and lime and the excrement of warm-bellied animals. The reason for this is that the virtue of the alterating heat remains in them along with the dry exhalation. Hence, since he had said that the cause of the saltness of the sea was the dry exhalation resolved from dried-out earth, it follows that the sea will also derive an abundance of warmth therefrom.
Deinde cum dicit: fit igitur semper alterum etc., excludit quasdam dubitationes circa praedicta. Et circa hoc duo facit: 174. Then at [180] he excludes some doubts on the aforesaid. About this he does two things:

primo excludit dubitationes;

secundo concludit ex praemissis causam salsedinis maris, ibi: nunc autem tantum et cetera.

First, he excludes the doubts;

Secondly, from what has gone before he concludes to the cause of the saltiness of the sea, at 176.

Prima dividitur in duas, secundum duas dubitationes quas solvit. Est autem prima dubitatio: cum aqua maris non continue maneat eadem numero secundum partes, sed evaporet et iterum cadat, non videtur esse causa salsedinis maris exhalatio sicca admixta, sed magis evaporatio ab aqua salsa. The first is divided into two parts according to the two doubts solved; [The second one is solved at 175.] The first doubt [180] is that since the water of the sea does not continue to have numerically the same parts but evaporates and re-descends, it does not seem that the cause of the saltness of the sea is the mixed-in dry exhalation, but rather an evaporation from salt water.
Et ad hanc dubitationem tollendam, dicit quod aqua maris semper fit altera et altera secundum partes, et quaelibet pars habet in sui generatione praedictam causam salsedinis, idest admixtionem terrestris exhalationis. Verum est etiam quod semper aliqua pars aquae salsae elevatur per evaporationem cum dulci: sed cum citius evaporet subtile quam grossum, et dulce est subtilius quam salsum, oportet quod minus de salso elevetur quam de dulci; sed per admixtionem exhalationis siccae, illud dulce accrescit iterum in salsedinem; et sic mare semper conservatur aequale et in quantitate et in salsedine. Et hoc ut ad totum, idest per comparationem ad totum mare, conservatur aequale vel quasi aequale: non enim semper punctalis conservatur praedicta quantitas. To remove this doubt he says that the water of the sea is forever becoming other and other as to its parts, and each part has in its generation the aforesaid cause of saltness, namely, the admixture of the earthy exhalation. Now it is also true that some part of the salt water is always being borne aloft with the sweet through evaporation — but since something refined evaporates more quickly than something dense, and the sweet is more refined than the salty, necessarily less of the salty than of the sweet is elevated; but through being mixed with the dry exhalation the sweet again grows in saltness, and thus the sea is forever maintained constant both in quantity and in salt. And this is said of the sea "as a whole," i.e., so far as the whole sea is concerned, it is kept constant or practically so — for the aforesaid quantity is not always kept absolutely exactly.
Secundam dubitationem solvit ibi: quod autem fit vaporans et cetera. Et est haec dubitatio: cum aqua maris sit salsa, unde contingit quod e vaporibus resolutis ab aqua maris generatur aqua dulcis? 175. The solution of the second doubt is at [181]. The doubt is this: since the water of the sea is salty, what accounts for the fact that sweet water is generated from the vapors resolved from the waters of the sea?
Et ad hoc solvendum dicit: iterum dicendum est quod illud quod evaporat in mari, quando condensatur, fit aqua potabilis et dulcis; et ideo non convertitur in mare, idest in aquam salsam, sed in aquam simpliciter. Et hoc idem patiuntur alia; sicut vinum et omnes humores, cum condensantur, convertuntur in aquam simpliciter; cum enim evaporant, vapores illi condensati convertuntur in aquam. Et huius ratio est, quia principium omnium humorum est aqua; resolvuntur autem omnia in sua principia. Omnia autem alia humida generantur ex aqua per aliquam passionem vel alterationem; quae passiones variantur propter admixtionem, et fit sapor eius secundum conditionem eius quod miscetur. Et propter hoc in generatione variatur aqua, et fit salsa. Sed quia unumquodque resolvitur in suum principium simpliciter, ut dictum est, consequens est ut tam ex aqua maris salsa, quam ex omnibus humoribus, cuiuscumque sint vaporis, per evaporationem generetur aqua simpliciter. To answer this he says that we must repeat that what evaporates in the sea becomes, when it is condensed, drinkable and sweet; therefore, it is not converted back into "sea," i.e., into salt water, but into fresh water. This happens to other things: wine and all liquids, when they are condensed, are turned into simple water: for when they evaporate, their condensed vapors are turned into water. The reason for this is that the principle of all moisture is water, and all things are resolved into their principles. Now all other liquids are generated from water which is affected or altered in some way, which affections vary according to the ingredients, and the savor depends on what is mixed in. This explains why, in the process of being generated, water varies and becomes salty. But because each thing is resolved into its principle absolutely, as has been said, the consequence is that whether it is salty sea water, or any liquid whatsoever of any vapor [savor?] you wish, the product of evaporation is simple water.
Deinde cum dicit: nunc autem tantum etc., ex omnibus praemissis colligit causam de salsedine maris. Et dicit quod nunc dicendum est quod semper aliqua pars aquae maris sursum ducitur per evaporationem, et fit potabilis quando condensatur: et iterum cum aqua desursum pluente descendit aliquid terrestre, quod non fuit sursum ductum ex aqua maris, sed ex arida. Et hoc terrestre, propter pondus, subsidet potabili et dulci; ut sic quod est subtilius, magis evaporet. Et ideo, propter continuam generationem et corruptionem, non deficit mare, sicut nec fluvii; nisi forte hoc accidat in aliquibus locis, tam in mari quam in fluviis, secundum aliquas determinatas periodos, ut supra dictum est. Nec tamen semper eaedem partes remanent aut maris aut terrae, sed solum tota moles utriusque. Sic enim oportet existimare de terra, sicut de mari, quod una pars sursum elevatur per exhalationem, et alia descendit; et quod etiam illa quae supernatant et quae descendunt, transmutant loca, ut sic quaelibet pars utriusque corrumpi et generari possit. 176. Then [182] from all the foregoing he gathers the cause of the salt of the sea. And he says that we must now say that some portion of the water of the sea is forever being raised aloft by evaporation and becomes drinkable when it is condensed; and further, that with the falling water there descends something terrestrial which was borne aloft, not from the water of the sea, but from dry land. And this terrestrial element because of its weight, sinks below the drinkable and sweet portion, with the result that the finer portion evaporates more. And therefore, as a result of continuous generation and evaporation, neither the sea nor rivers disappear: unless they happen to disappear in certain regions according to certain definite cycles, as mentioned earlier. Moreover, neither do the same parts of the sea or of the earth always remain, but only the whole bulks of both. Thus, we must think of the earth as we do of the sea, namely, that one part is borne aloft through exhalation and another part descends and, furthermore, that the parts on the surface exchange places with those that descend: as a result, every part of both can be corrupted and generated.
Considerandum est autem quod supra Aristoteles, causam salsedinis maris assignans, ubi tractavit de loco naturali aquae, dixit quod salsedo maris causatur per evaporationem eius quod est subtile et dulce. Haec autem causa nulla esset, si in aqua maris nihil alienum admisceretur: quia oporteret hoc etiam quod remanet, esse dulce et potabile, secundum simplicis aquae naturam. Et ideo, ad ostendendum quomodo aqua maris sit salsa, ostendit quod sit aliquid extraneum admixtum, quod subsidens post elevationem dulcis potabilis, reddit aquam maris salsam: et propter hoc dicit terrestre adustum esse admixtum vaporibus ex quibus generatur aqua. Unde, cum quaelibet pars maris sic generetur, relinquitur quod singulis partibus maris sit huiusmodi terrestre admixtum, quod secundum plurimum subsidet dulci et subtili, in maiori parte elevato. It should be noted that Aristotle, in assigning the cause of the saltness of the sea when treating of the natural place of water above, stated that the saltness of the sea is caused by the evaporation of what is fine and sweet. But this would not be a cause, if nothing foreign were mixed in the sea water — since it would be necessary that what remained be sweet and drinkable, according to the nature of simple water. Consequently, in order to show how the water of the sea is salty, he shows that something foreign is mixed in it, which sinks (after the sweet potable water is elevated) and makes the water of the sea salty. On this account he says that burnt earth is mixed with the vapors from which water is generated. Hence, since each part of the sea is thus generated, it follows that a terrestrial adjunct of this sort is mixed with every part of the sea, and generally sinks below the sweet and fine, the major portion of which is elevated.
Et quia ex eo quod evaporat generatur aqua dulcis, omnis autem aqua fontium et fluviorum ex eo quod evaporat generatur, vel supra terram vel infra terram, consequens est ut aqua fontium et fluviorum sit dulcis, utpote propinqua principio generationis; aqua autem maris sit salsa, utpote residuum existens vaporum elevatorum a sole, et ultimus terminus in quem aquae generatae colliguntur. And because sweet water is generated out of what evaporates, and all the water of springs and rivers is generated out of what evaporates, either on the surface of the earth or below the earth, it follows that the water of springs and rivers is sweet, simply because they are close to the source of generation; but the water of the sea is salty, being both the residue of vapors elevated by the sun and the final terminus into which the generated water is collected.
Deinde cum dicit: quod autem est in commixtione etc., manifestat quod ex commixtione terrestris causatur salsus sapor. Et ponit multa signa. Quorum primum est de vase cereo, quod si claudatur et ponatur in aqua, quod resudat interius efficitur dulce, tanquam depurato terrestri per ceram. 177. Then [183] he manifests that the salty savor is caused from a terrestrial mixture. And he gives many signs. The first of these concerns a waxen container sealed and set in water. Whatever seeps in becomes sweet, as though the terrestrial stuff were filtered out by the wax.
Aliud signum est, quod aqua maris plus ponderat quam dulcis. Another sign is that sea water is heavier than the sweet.
Tertium signum est, quod aqua maris est grossior quam aqua fluviorum, ita quod naves oneratae plus profundantur in aquis fluviorum quam maris. A third sign is that sea water is denser than river water, so that ships laden with cargo sink deeper in rivers than in the sea.
Quartum signum est, quod ova, si sint plena, supernatant in aqua quae fit salsa per admixtionem salis, et etiam supernatant in mari. Unde et mare videtur sicut lutum, propter grossitiem. Et hoc faciunt salientes, ut accipiant signum si sal sit bene mixtum aqua, ex hoc quod ova supernatant. Igitur et aqua maris est grossa per admixtionem alicuius terrestris ingrossantis. The fourth sign is that eggs, if full, float in water to which salt has been added and even float in the sea. Hence the sea seems to be like mud on account of its density. Those who make brine take as a sign that the salt has been well mixed with the water, when eggs float on it. Therefore, sea water, too, is dense on account of an admixture of some gross earthy stuff.
Quintum signum est, quod in stagno Palestinae, quod est salsum vel amarum, si quis immerserit hominem vel asinum, non submergitur; et vestimenta ibi perfusa foedantur. The fifth sign is that in the lake in Palestine which is salty or bitter, if anyone should immerse a man or ass, it does not sink; and clothing dipped in it becomes fetid.
Sextum autem signum est de quodam fonte aquae latae, idest salsae, in provincia Chaoniae, qui effluit in quendam fluvium dulcem, sed non habentem pisces; in quo quidem fluvio, propter admixtionem fontis, inventi sunt aliquando sales pro piscibus; cuius quidem aqua vertitur per decoctionem in sales, evaporante calido et humido. Huiusmodi autem sales non sunt spissi, sed subtiles sicut nix; et sunt debiliores aliis, et isti in cibariis magis delectant. The sixth sign concerns a spring of "broad," i.e., salt, water in the province of Chaonia. This spring flows into a river of fresh water in which are no fish, but on account of the mixture contributed by this spring, salt is sometimes found instead of fish. When this water is boiled, salt is left after what is hot and liquid has evaporated. These salts are not coarse but fine as snow; they are weaker than other salts and give greater pleasure in foods.
Septimum autem signum est, quod in quodam loco calami et scirpi comburuntur, et eorum cinis, dum in aqua decoquitur, post infrigidationem efficitur sal, secundum terrestris combusti mixtionem, quam dixerat esse causam salsedinis. Unde oportet quod tam in aqua horum cinerum quam in aqua maris, combustio sit quae causet salsedinem. Et hinc est quod universaliter quaecumque aqua fluens fontium vel fluviorum est salsa, aliquando fuit calida, utpote ex terra ignita procedens: sed postea ignis extinguitur infra terram, et terra quae ex combustione fit sulphurea vel aliquid huiusmodi, remanet adhuc combusta ad modum calcis vel cineris: unde aqua transiens per eam fit salsa. Et non solum fit salsa, et salsedinem recipit aqua ex terra per quam transit, sed etiam alios sapores, ut manifestat per quaedam exempla: et littera plana est. The seventh sign is that there is a region in which reeds and rushes are burned. When their ash is cooked in water and cooled, it becomes salty to a degree depending on the proportion of burned earthy matter, which he had said is the cause of saltiness. Hence, both in the water of these ashes, as well as in the water of the sea, there must be a combustion which causes saltiness. This is why universally any flowing water of springs and rivers which is salty, was once hot, as though proceeding from ignited earth. Afterwards the fire is extinguished within the earth, which, by the burning, having become sulphurous or something of the sort, still retains the marks of having been burnt, as lime and ashes do — so that water passing through it becomes salty. Indeed, such water not only becomes salty and receives saltness from the earth through which it passes, but also other savors, as he explains with examples (and this is plain in the text).
Ultimo autem recapitulat ea quae dicta sunt: et hoc etiam est planum in littera. Finally, he sums up what has been said — and this is also plain in the text.

Lecture 7
On the generation of winds
Chapter 4
περὶ δὲ πνευμάτων λέγωμεν, λαβόντες ἀρχὴν τὴν εἰρημένην ἡμῖν ἤδη πρότερον. ἔστι γὰρ δύ' εἴδη τῆς ἀναθυμιάσεως, ὥς φαμεν, ἡ μὲν ὑγρὰ ἡ δὲ ξηρά καλεῖται δ' ἡ μὲν ἀτμίς, ἡ δὲ τὸ μὲν ὅλον ἀνώνυμος, τῷ δ' ἐπὶ μέρους ἀνάγκη χρωμένους καθόλου προσαγορεύειν αὐτὴν οἷον καπνόν ἔστι δ' οὔτε τὸ ὑγρὸν ἄνευ τοῦ ξηροῦ οὔτε τὸ ξηρὸν ἄνευ τοῦ ὑγροῦ, ἀλλὰ πάντα ταῦτα λέγεται κατὰ τὴν ὑπεροχήν. 185 Let us proceed to the theory of winds. Its basis is a distinction we have already made. We recognize two kinds of evaporation, one moist, the other dry. The former is called vapour: for the other there is no general name but we must call it a sort of smoke, applying to the whole of it a word that is proper to one of its forms. The moist cannot exist without the dry nor the dry without the moist: whenever we speak of either we mean that it predominates.
φερομένου δὴ τοῦ ἡλίου κύκλῳ, καὶ ὅταν μὲν πλησιάζῃ, τῇ θερμότητι ἀνάγοντος τὸ ὑγρόν, πορρωτέρω (360a.) δὲ γιγνομένου διὰ τὴν ψύξιν συνισταμένης πάλιν τῆς ἀναχθείσης ἀτμίδος εἰς ὕδωρ (διὸ χειμῶνός τε μᾶλλον γίγνεται τὰ ὕδατα, καὶ νύκτωρ ἢ μεθ' ἡμέραν ἀλλ' οὐ δοκεῖ, διὰ τὸ λανθάνειν τὰ νυκτερινὰ τῶν μεθ' ἡμέραν μᾶλλον), τὸ δὴ κατιὸν ὕδωρ διαδίδοται πᾶν εἰς τὴν γῆν, ὑπάρχει δ' ἐν τῇ γῇ πολὺ πῦρ καὶ πολλὴ θερμότης, καὶ ὁ ἥλιος οὐ μόνον τὸ ἐπιπολάζον τῆς γῆς ὑγρὸν ἕλκει, ἀλλὰ καὶ τὴν γῆν αὐτὴν ξηραίνει θερμαίνων 186 Now when the sun in its circular course approaches, it draws up by its heat the moist evaporation: when it recedes the cold makes the vapour that had been raised condense back into water which falls and is distributed through the earth. (This explains why there is more rain in winter and more by night than by day: though the fact is not recognized because rain by night is more apt to escape observation than by day.) But there is a great quantity of fire and heat in the earth, and the sun not only draws up the moisture that lies on the surface of it, but warms and dries the earth itself.
τῆς δ' ἀναθυμιάσεως, ὥσπερ εἴρηται, διπλῆς οὔσης, τῆς μὲν ἀτμιδώδους τῆς δὲ καπνώδους, ἀμφοτέρας ἀναγκαῖον γίγνεσθαι. τούτων δ' ἡ μὲν ὑγροῦ πλέον ἔχουσα πλῆθος ἀναθυμίασις ἀρχὴ τοῦ ὑομένου ὕδατός ἐστιν, ὥσπερ εἴρηται πρότερον, ἡ δὲ ξηρὰ τῶν πνευμάτων ἀρχὴ καὶ φύσις πάντων. 187 Consequently, since there are two kinds of evaporation, as we have said, one like vapour, the other like smoke, both of them are necessarily generated. That in which moisture predominates is the source of rain, as we explained before, while the dry evaporation is the source and substance of all winds.
ταῦτα δὲ ὅτι τοῦτον τὸν τρόπον ἀναγκαῖον συμβαίνειν, καὶ ἐξ αὐτῶν τῶν ἔργων δῆλον καὶ γὰρ τὴν ἀναθυμίασιν διαφέρειν ἀναγκαῖον, καὶ τὸν ἥλιον καὶ τὴν ἐν τῇ γῇ θερμότητα ταῦτα ποιεῖν οὐ μόνον δυνατὸν ἀλλ' ἀναγκαῖόν ἐστιν. 188 That things must necessarily take this course is clear from the resulting phenomena themselves, for the evaporation that is to produce them must necessarily differ; and the sun and the warmth in the earth not only can but must produce these evaporations.
ἐπειδὴ δ' ἕτερον ἑκατέρας τὸ εἶδος, φανερὸν ὅτι διαφέρει, καὶ οὐχ ἡ αὐτή ἐστιν ἥ τε ἀνέμου φύσις καὶ ἡ τοῦ ὑομένου ὕδατος, καθάπερ τινὲς λέγουσιν τὸν γὰρ αὐτὸν ἀέρα κινούμενον μὲν ἄνεμον εἶναι, συνιστάμενον δὲ πάλιν ὕδωρ. ὁ μὲν οὖν ἀήρ, καθάπερ ἐν τοῖς πρὸ τούτων λόγοις εἰρήκαμεν, γίγνεται ἐκ τούτων ἡ μὲν γὰρ ἀτμὶς ὑγρὸν καὶ ψυχρόν (εὐόριστον μὲν γὰρ ὡς ὑγρόν, διὰ δὲ τὸ ὕδατος εἶναι ψυχρὸν τῇ οἰκείᾳ φύσει, ὥσπερ ὕδωρ μὴ θερμανθέν), ὁ δὲ καπνὸς θερμὸν καὶ ξηρόν ὥστε καθάπερ ἐκ συμβόλων, συνίσταιτο ἂν ὁ ἀὴρ ὑγρὸς καὶ θερμός. 189 Since the two evaporations are specifically distinct, wind and rain obviously differ and their substance is not the same, as those say who maintain that one and the same air when in motion is wind, but when it condenses again is water. Air, as we have explained in an earlier book, is made up of these as constituents. Vapour is moist and cold (for its fluidity is due to its moistness, and because it derives from water it is naturally cold, like water that has not been warmed): whereas the smoky evaporation is hot and dry. Hence each contributes a part, and air is moist and hot.
καὶ γὰρ ἄτοπον εἰ ὁ περὶ ἑκάστους περικεχυμένος ἀὴρ οὗτος γίγνεται κινούμενος πνεῦμα, καὶ ὅθεν ἂν τύχῃ κινηθείς, ἄνεμος ἔσται, ἀλλ' οὐ καθάπερ τοὺς ποταμοὺς ὑπολαμβάνομεν οὐχ ὁπωσοῦν τοῦ ὕδατος εἶναι ῥέοντος, οὐδ' ἂν ἔχῃ πλῆθος, ἀλλὰ δεῖ πηγαῖον εἶναι τὸ ῥέον οὕτω γὰρ καὶ περὶ τῶν ἀνέμων ἔχει κινηθείη γὰρ ἂν πολὺ πλῆθος ἀέρος ὑπό τινος μεγάλης πτώσεως, οὐκ ἔχον ἀρχὴν οὐδὲ πηγήν. 190 It is absurd that this air that surrounds us should become wind when in motion, whatever be the source of its motion on the contrary the case of winds is like that of rivers. We do not call water that flows anyhow a river, even if there is a great quantity of it, but only if the flow comes from a spring. So too with the winds; a great quantity of air might be moved by the fall of some large object without flowing from any source or spring.
μαρτυρεῖ δὲ τὰ γιγνόμενα τοῖς εἰρημένοις διὰ γὰρ τὸ συνεχῶς μὲν μᾶλλον δὲ καὶ ἧττον καὶ πλείω καὶ ἐλάττω γίγνεσθαι τὴν (360b.) ἀναθυμίασιν, ἀεὶ νέφη τε καὶ πνεύματα γίγνεται κατὰ τὴν ὥραν ἑκάστην ὡς πέφυκεν διὰ δὲ τὸ ἐνίοτε μὲν τὴν ἀτμιδώδη γίγνεσθαι πολλαπλασίαν ὁτὲ δὲ τὴν ξηρὰν καὶ καπνώδη, ὁτὲ μὲν ἔπομβρα τὰ ἔτη γίγνεται καὶ ὑγρά, ὁτὲ δὲ ἀνεμώδη καὶ αὐχμοί. ὁτὲ μὲν οὖν συμβαίνει καὶ τοὺς αὐχμοὺς καὶ τὰς ἐπομβρίας πολλοὺς ἅμα καὶ κατὰ συνεχῆ γίγνεσθαι χώραν, ὁτὲ δὲ κατὰ μέρη πολλάκις γὰρ ἡ μὲν κύκλῳ χώρα λαμβάνει τοὺς ὡραίους ὄμβρους ἢ καὶ πλείους, ἐν δέ τινι μέρει ταύτης αὐχμός ἐστιν ὁτὲ δὲ τοὐναντίον τῆς κύκλῳ πάσης ἢ μετρίοις χρωμένης ὕδασιν ἢ καὶ μᾶλλον αὐχμώσης, ἕν τι μόριον ὕδατος ἄφθονον λαμβάνει πλῆθος. αἴτιον δ' ὅτι ὡς μὲν τὰ πολλὰ τὸ αὐτὸ πάθος ἐπὶ πλείω διήκειν εἰκὸς χώραν, διὰ τὸ παραπλησίως κεῖσθαι πρὸς τὸν ἥλιον τὰ σύνεγγυς, ἐὰν μή τι διάφορον ἔχωσιν ἴδιον οὐ μὴν ἀλλ' ἐνίοτε κατὰ τοδὶ μὲν τὸ μέρος ἡ ξηρὰ ἀναθυμίασις ἐγένετο πλείων, κατὰ δὲ τὸ ἄλλο ἡ ἀτμιδώδης, ὁτὲ δὲ τοὐναντίον. καὶ αὐτοῦ δὲ τούτου αἴτιον τὸ ἑκατέραν μεταπίπτειν εἰς τὴν τῆς ἐχομένης χώρας ἀναθυμίασιν, οἷον ἡ μὲν ξηρὰ κατὰ τὴν οἰκείαν ῥεῖ χώραν, ἡ δ' ὑγρὰ πρὸς τὴν γειτνιῶσαν, ἢ καὶ εἰς τῶν πόρρω τινὰ τόπων ἀπεώσθη ὑπὸ πνευμάτων ὁτὲ δὲ αὕτη μὲν ἔμεινεν, ἡ δ' ἐναντία ταὐτὸν ἐποίησεν. καὶ συμβαίνει τοῦτο πολλάκις, ὥσπερ ἐπὶ τοῦ σώματος, ἐὰν ἡ ἄνω κοιλία ξηρὰ ᾖ, τὴν κάτω ἐναντίως διακεῖσθαι, καὶ ταύτης ξηρᾶς οὔσης ὑγρὰν εἶναι τὴν ἄνω καὶ ψυχράν, οὕτω καὶ περὶ τοὺς τόπους ἀντιπεριίστασθαι καὶ μεταβάλλειν τὰς ἀναθυμιάσεις. 191 The facts bear out our theory. It is because the evaporation takes place uninterruptedly but differs in degree and quantity that clouds and winds appear in their natural proportion according to the season; and it is because there is now a great excess of the vaporous, now of the dry and smoky exhalation, that some years are rainy and wet, others windy and dry. Sometimes there is much drought or rain, and it prevails over a great and continuous stretch of country. At other times it is local; the surrounding country often getting seasonable or even excessive rains while there is drought in a certain part; or, contrariwise, all the surrounding country gets little or even no rain while a certain part gets rain in abundance. The reason for all this is that while the same affection is generally apt to prevail over a considerable district because adjacent places (unless there is something special to differentiate them) stand in the same relation to the sun, yet on occasion the dry evaporation will prevail in one part and the moist in another, or conversely. Again the reason for this latter is that each evaporation goes over to that of the neighbouring district: for instance, the dry evaporation circulates in its own place while the moist migrates to the next district or is even driven by winds to some distant place: or else the moist evaporation remains and the dry moves away. Just as in the case of the body when the stomach is dry the lower belly is often in the contrary state, and when it is dry the stomach is moist and cold, so it often happens that the evaporations reciprocally take one another's place and interchange.
ἔτι δὲ μετά τε τοὺς ὄμβρους ἄνεμος ὡς τὰ πολλὰ γίγνεται ἐν ἐκείνοις τοῖς τόποις καθ' οὓς ἂν συμπέσῃ γενέσθαι τοὺς ὄμβρους, καὶ τὰ πνεύματα παύεται ὕδατος γενομένου. ταῦτα γὰρ ἀνάγκη συμβαίνειν διὰ τὰς εἰρημένας ἀρχάς ὕσαντός τε γὰρ ἡ γῆ ξηραινομένη ὑπό τε τοῦ ἐν αὐτῇ θερμοῦ καὶ ὑπὸ τοῦ ἄνωθεν ἀναθυμιᾶται, τοῦτο δ' ἦν ἀνέμου σῶμα καὶ ὅταν ἡ τοιαύτη ἀπόκρισις ᾖ καὶ ἄνεμοι κατέχωσι, παυομένων διὰ τὸ ἀποκρίνεσθαι τὸ θερμὸν ἀεὶ καὶ ἀναφέρεσθαι εἰς τὸν ἄνω τόπον συνίσταται ἡ ἀτμὶς ψυχομένη καὶ γίγνεται ὕδωρ (361a.) καὶ ὅταν εἰς ταὐτὸν συνωσθῶσι τὰ νέφη καὶ ἀντιπεριστῇ εἰς αὐτὰ ἡ ψύξις, ὕδωρ γίγνεται καὶ καταψύχει τὴν ξηρὰν ἀναθυμίασιν. παύουσί τε οὖν τὰ ὕδατα γιγνόμενα τοὺς ἀνέμους, καὶ παυομένων αὐτὰ γίγνεται διὰ ταύτας τὰς αἰτίας. 192 Further, after rain wind generally rises in those places where the rain fell, and when rain has come on the wind ceases. These are necessary effects of the principles we have explained. After rain the earth is being dried by its own heat and that from above and gives off the evaporation which we saw to be the material cause of. wind. Again, suppose this secretion is present and wind prevails; the heat is continually being thrown off, rising to the upper region, and so the wind ceases; then the fall in temperature makes vapour form and condense into water. Water also forms and cools the dry evaporation when the clouds are driven together and the cold concentrated in them. These are the causes that make wind cease on the advent of rain, and rain fall on the cessation of wind.
ἔτι δὲ τοῦ γίγνεσθαι μάλιστα πνεύματα ἀπό τε τῆς ἄρκτου καὶ μεσημβρίας τὸ αὐτὸ αἴτιον πλεῖστοι γὰρ βορέαι καὶ νότοι γίγνονται τῶν ἀνέμων ὁ γὰρ ἥλιος τούτους μόνους οὐκ ἐπέρχεται τοὺς τόπους, ἀλλὰ πρὸς τούτους καὶ ἀπὸ τούτων, ἐπὶ δυσμὰς δὲ καὶ ἐπ' ἀνατολὰς ἀεὶ φέρεται διὸ τὰ νέφη συνίσταται ἐν τοῖς πλαγίοις, καὶ γίγνεται προσιόντος μὲν ἡ ἀναθυμίασις τοῦ ὑγροῦ, ἀπιόντος δὲ πρὸς τὸν ἐναντίον τόπον ὕδατα καὶ χειμῶνες. διὰ μὲν οὖν τὴν φορὰν τὴν ἐπὶ τροπὰς καὶ ἀπὸ τροπῶν θέρος γίγνεται καὶ χειμών, καὶ ἀνάγεταί τε ἄνω τὸ ὕδωρ καὶ γίγνεται πάλιν ἐπεὶ δὲ πλεῖστον μὲν καταβαίνει ὕδωρ ἐν τούτοις τοῖς τόποις ἐφ' οὓς τρέπεται καὶ ἀφ' ὧν, οὗτοι δέ εἰσιν ὅ τε πρὸς ἄρκτον καὶ μεσημβρίαν, ὅπου δὲ πλεῖστον ὕδωρ ἡ γῆ δέχεται, ἐνταῦθα πλείστην ἀναγκαῖον γίγνεσθαι τὴν ἀναθυμίασιν παραπλησίως οἷον ἐκ χλωρῶν ξύλων καπνόν, ἡ δ' ἀναθυμίασις αὕτη ἄνεμός ἐστιν, εὐλόγως ἂν οὖν ἐντεῦθεν γίγνοιτο τὰ πλεῖστα καὶ κυριώτατα τῶν πνευμάτων. καλοῦνται δ' οἱ μὲν ἀπὸ τῆς ἄρκτου βορέαι, οἱ δὲ ἀπὸ τῆς μεσημβρίας νότοι. 193 The cause of the predominance of winds from the north and from the south is the same. (Most winds, as a matter of fact, are north winds or south winds.) These are the only regions which the sun does not visit: it approaches them and recedes from them, but its course is always over the west and the east. Hence clouds collect on either side, and when the sun approaches it provokes the moist evaporation, and when it recedes to the opposite side there are storms and rain. So summer and winter are due to the sun's motion to and from the solstices, and water ascends and falls again for the same reason. Now since most rain falls in those regions towards which and from which the sun turns and these are the north and the south, and since most evaporation must take place where there is the greatest rainfall, just as green wood gives most smoke, and since this evaporation is wind, it is natural that the most and most important winds should come from these quarters. (The winds from the north are called Boreae, those from the south Noti.)
Postquam philosophus determinavit de mari, cuius salsedo causatur ex admixtione exhalationis siccae terrestris, consequenter determinat de ventis, qui ab eadem exhalatione sicca causantur. Et dividitur in partes duas: 178. After determining about the sea, whose saltness is caused from an admixture of the dry earthy exhalation, the Philosopher subsequently determines about the winds, which are caused by the same dry exhalation. And it is divided into two sections:

in prima determinat de ipsis ventis;

in secunda de quibusdam passionibus ex ventis causatis, ibi: de agitatione autem et motu et cetera.

In the first he determines about the winds themselves, at 179;

In the second about certain phenomena caused from winds (c. 7).

Prima iterum dividitur in duas: The first is divided into two parts:

in prima determinat de ventis in communi;

in secunda de speciebus ventorum, ibi: de positione et cetera.

In the first he determines about winds in general;

In the second about the species of winds (c. 6).

Prima dividitur in tres partes: The first is divided into three parts:

in prima determinat de generatione ventorum;

in secunda de motu locali eorum, ibi: latio autem ipsorum etc.;

in tertia de augmento et quietatione ipsorum, ibi: sol autem et cessare et cetera.

In the first he determines about the generation of winds, at 179;

In the second about their local motion (L. 8);

In the third about their increase and abatement (L. 9).

Circa primum tria facit: Regarding the first he does three things:

primo praemittit principia generationis ventorum;

secundo ponit modum generationis eorum, ibi: exhalatione autem sicut etc.;

tertio manifestat quod dictum est, ibi: hoc autem quod isto modo et cetera.

First, he lays down the principles of the generation of winds, at 179;

Secondly, he describes the manner of their generation, at 181;

Thirdly, he manifests what has been said, at 182.

Circa primum duo facit. Primo assignat principium materiale ventorum. Et dicit quod, cum dicendum est de spiritibus, idest de ventis, oportet resumere hoc principium, quod iam prius dictum est, scilicet quod sunt duae species exhalationis: una quidem humida, quae vocatur vapor; alia autem sicca, quae, quia non habet nomen commune, a quadam sui parte vocetur fumus; nam fumus proprie dicitur exhalatio sicca lignorum ignitorum. Duae autem hae exhalationes non sic discretae sunt ad invicem, quod humidum sit sine sicco, et siccum sine humido: sed ab eo quod excedit, utraque denominatur. 179. Regarding the first he does two things: first he assigns the material principle of winds [185] and says that, since "spirits," i.e., winds, are to be discussed, it is necessary to recall this principle, already enunciated, namely, that there are two kinds of exhalation: one, indeed, is the moist, which is called "vapor"; the other is the dry, which, having no common name, is called "smoke" from one of its forms: for smoke is, strictly speaking, the dry exhalation of burning wood. Now these two exhalations are not so independent of each other that the moist is without the dry, and the dry without the moist — rather they are denominated one or the other by that which is predominant in a given case.
Secundo ibi: lato autem sole etc., ponit principium efficiens, quod est motus solis. Et dicit quod cum sol suo motu appropinquat ad aliquam partem terrae, sua caliditate elevat humidum: eo autem elongato, vapor elevatus, propter frigiditatem, condensatur in aquam. Et inde est quod in hieme magis pluit quam in aestate, et in nocte quam in die, licet aquae nocturnae lateant propter somnum. Aqua autem pluens dividitur per terram, et bibitur ab ea. In terra autem est multum de calore, ex actione solis et aliorum corporum caelestium; et sol desuper eam calefaciens, non solum attrahit per evaporationem humidum quod supernatat terrae, ut puta aquam maris, fluviorum et stagnorum, sed etiam ipsam terram desiccat, attrahens humorem imbibitum in terra. Quod ergo exhalat ab humido supernatante, dicitur vapor: quod autem exhalat per desiccationem terrae, dicitur fumus; sicut in simili dicitur fumus, quod exhalat a lignis calefactis. 180. Secondly [186], he mentions the efficient principle, which is the motion of the sun. And he says that when the sun in its course approaches a given region of the earth, its warmth elevates the moist; as the sun recedes, this raised vapor is condensed into water on account of the cold. This is why there is more rain in winter than in summer, and more at night than during the day, although night-rains go unobserved because of sleep. The rain water is divided up in the earth and drunk in by it. In the earth much heat exists, caused by the action of the sun and other heavenly bodies. And the sun overhead, heating the earth, not only draws aloft the moisture resting on the surface of the earth — for example, the water of the sea, rivers and ponds — but also dries out the earth itself and draws up the moisture drunk by the earth. Consequently the exhalation it produces from the moisture resting on the earth is called "vapor," but the exhalation that results from its drying out the earth is called "smoke," just as in a parallel case, the exhalation from heated wood is called "smoke. "
Deinde cum dicit: exhalatione autem sicut etc., determinat generationem ventorum. Et dicit quod, cum exhalatio duplex sit, ut dictum est, una vaporosa et alia fumosa, necesse est quod ex motu solis fiat utraque. Ea autem quae plus habet de humido, est principium pluentis aquae, ut supra dictum est (quod dicit propter hoc, quia supra dixerat ei admisceri aliquid de exhalatione sicca): sicca autem exhalatio est principium ventorum. 181. Then [187] he determines the generation of winds and says that since exhalations are of two kinds, as has been said, one vaporous and one smoky, it is necessary that, from the sun's motion, both should come about. The one with more moisture is the source of rain water, as said above (which he says, because he had previously stated that some dry exhalation is mixed with it); but the dry exhalation is the source of winds.
Deinde cum dicit: hoc autem quod isto modo etc., manifestat quod dictum est de generatione ventorum. Et circa hoc tria facit: 182. Then [188] he manifests what has been said about the generation of winds. About this he does three things:

primo hoc manifestat per rationem;

secundo ex hoc quod dictum est, excludit falsas opiniones de ventis, ibi: quoniam autem altera etc.;

tertio hoc manifestat per signa, ibi: attestantur autem quae fiunt et cetera.

First, he manifests it with an argument;

Secondly, from what has been said, he excludes false opinions about winds, at 183;

Thirdly, he manifests this with signs, at 185.

Dicit ergo primo quod, cum sit duplex exhalatio, propter duo ex quibus consurgit, scilicet terram et aquam, possibile est, immo necessarium, quod sol et caliditas quae est circa terram, possit causare resolutionem utriusque exhalationis. He says therefore first [188] that since exhalations are of two kinds, on account of the two sources from which they are derived, namely, earth and water, it is possible, even necessary, that the sun and the heat which environs the earth can cause the resolution of both exhalations.
Deinde cum dicit: quoniam autem altera etc., excludit falsas opiniones de ventis. Et primo quantum ad hoc, quod dicebant quod eadem natura est venti et pluviae. Quod quidem excludit per hoc, quod diversorum diversi sunt effectus: unde, cum exhalationes differant secundum siccum et humidum, necesse est quod non sit eadem natura venti et natura aquae pluentis, ut quidam posuerunt, dicentes quod idem aer quando movetur, est ventus, quando autem condensatur, fit aqua. 183. Then [189] he dismisses false theories about the winds. First, the opinion of those who said that the natures of wind and of rain are the same. This he excludes by the fact that the effects of diverse things are themselves diverse: hence, since the exhalations differ on the basis of dry and moist, it is necessary that the nature of wind and of rain water be not the same, as some supposed who said that it is the same air which, when moved, is wind, and when condensed, becomes water.
Sed, sicut dictum est in libro de generatione, aer habet aliquid vaporis et aliquid fumi. Vapor eius est frigidus et humidus, et bene terminabilis, propter grossitiem: et hoc convenit aeri inquantum est humidus. Sic etiam vapor, qui elevatur ab aqua, est frigidus secundum suam naturam, sicut et aqua non calefacta: sicut autem aqua calefacta remanet frigida secundum naturam, ita et vapor. Sed fumus est calidus et siccus: siccus quidem propter terram, calidus autem propter ignem. Unde manifeste patet quod superior aer, qui est calidus et humidus, habet similitudinem cum utroque. But as stated in On Generation, air has something of vapor and of smoke. Its vapor is cold and moist and well-definable by its density; and this belongs to air in so far as it is moist. Thus also vapor, which is borne up from water, is cold by its very nature, as also is unwarmed water: just as warmed water remains cold according to nature, so also vapor. But smoke is hot and dry: because of the earth, it is dry; because of fire, it is hot. Hence it is manifestly plain that the upper air, which is hot and moist, bears a likeness to both.
Secundo ibi: etenim inconveniens etc., excludit falsam opinionem quantum ad hoc, quod dicebant quod ventus nihil aliud est quam aer motus. Et dicit quod inconveniens est, si quis existimet quod iste aer qui circumstat unumquemque nostrum, quando movetur est ventus; vel quod unusquisque motus qui accidit in aere, sit ventus; sicut etiam non existimamus fluvium esse aquam qualitercumque fluentem, etiam si multa sit, sed solum quando fluit ex aliquo principio determinato, quod est fons ex terra scaturiens. Sic etiam est de ventis: non enim est ventus, si aer moveatur aliquo modo casu, etiam in magna multitudine, nisi habeat principium, quasi fontem, exhalationem siccam elevatam. Sic igitur non est verum quod aer motus est ventus: tum quia quandoque parvus aer movetur, tum quia non habet principium. 184. Secon