Question Eleven: The Teacher

Can a man or only God teach and be called teacher?
Can one be called his own teacher?
Can a man be taught by an angel?
Is teaching an activity of the contemplative or the active life?


The question treats of the teacher,

and in the first article we ask:

Can a man or only God teach and be called teacher?

[Parallel readings: II Sent., 9, 2, ad 4; 28, 5, ad 3; C.G., II, 75; S.T., I, 117, 1; De unit. intell., 5, nn. 50-51.]


It seems that only God teaches and should be called a teacher, for

1. In St. Matthew (2 3:8) we read: “One is your master”; and just before that: “Be not you called Rabbi.” On this passage the Gloss comments: “Lest you give divine honor to men, or usurp for yourselves what belongs to God.” Therefore, it seems that only God is a teacher, or teaches.

2. If a man teaches, he does so only through certain signs. For, even if one seems to teach by means of things, as, when asked what walking is, he walks, this is not sufficient to teach the one who asks, unless some sign be added, as Augustine proves. He does this by showing that there are many factors involved in the same action; hence, one will not know to what factor the demonstration was due, whether to the substance of the action or to some accident of it. Furthermore, one cannot come to a knowledge of things through a sign, for the knowledge of things is more excellent than the knowledge of signs, since the knowledge of signs is directed to knowledge of things as a means to an end. But the effect is not more excellent than its cause. Therefore, no one can impart knowledge of anything to another, and so cannot teach him.

3. If signs of certain things are proposed to someone by a man, the one to whom they are proposed either knows the things which the signs represent or he does not. If he knows the things, he is not taught them. But if he does not know them, he cannot know the meanings of the signs, since he does not know the things. For a man who does not know what a stone is cannot know what the word stone means. But if he does not know the meaning of the terms, he cannot learn anything through the signs. Therefore, if a man does nothing else to teach than propose signs, it seems that one man cannot be taught by another.

4. To teach is nothing else than to cause knowledge in another in some way. But our understanding is the subject of knowledge. Now, sensible signs, by which alone, it would seem, man can be taught, do not reach the intellective part, but affect the senses only. Therefore, man cannot be taught by a man.

5. If the knowledge is caused by one person in another, the learner either had it already or he did not. If he did not have it already and it was caused in him by another, then one man creates knowledge in another, which is impossible. However, if he had it already, it was present either in complete actuality, and thus it cannot be caused, for what already exists does not come into being, or it was present seminally (secundum rationes seminales). But such seminal principles cannot be actualized by any created power, but are implanted in nature by God alone, as Augustine says. So, it remains true that one man can in no way teach another.

6. Knowledge is an accident. But an accident does not change the subject in which it inheres. Therefore, since teaching seems to be nothing else but the transfer of knowledge from teacher to pupil, one cannot teach another.

7. The Gloss, on Romans (10:17), “Faith then cometh by hearing,” says: “Although God teaches man interiorly, the preacher proclaims it exteriorly.” But knowledge is caused interiorly in the mind, not exteriorly in the senses. Therefore, man is taught only by God, not by another man.

8. Augustine says: “God alone, who teaches truth on earth, holds the teacher’s chair in heaven, but to this chair another man has the relation which a farmer has to a tree.” But the farmer does not make the tree; he cultivates it. And by the same token no nian can bc said to teach knowledge, but only prepare the mind for it.

9. If man is a real teacher, he must teach the truth. But whoever teaches the truth enlightens the mind, for truth is the light of the mind. If, therefore, man does teach, he enlightens the mind. But this is false, for in the Gospel according to St. John (1:9) we see that it is God who “enlighteneth every man that cometh into this world.” Therefore, one man cannot really teach another.

10. If one man teaches another, he must make a potential knower into an actual knower. Therefore, his knowledge must be raised from potency to act. But what is raised from potency to actuality must be changed. Therefore, knowledge or wisdom will be changed. However, this is contrary to Augustine, who says: “In coming to a man, wisdom is not itself changed, but changes the man.”

11. Knowledge is nothing else but the representation of things in the soul, since knowledge is called the assimilation of the knower to the thing known. But one man cannot imprint the likeness of things in the soul of another. For, thus, he would work interiorly in that man, which God alone can do. Therefore, one man cannot teach another.

12. Boethius says that teaching does no more than stimulate the mind to know. But he who stimulates the understanding to know does not make it know, just as one who incites someone to see with the eyes of the body does not make him see. Therefore, one man does not make another know. And so it cannot properly be said that he teaches him.

13. There is no scientific knowledge without certitude. Otherwise, it is not scientific knowledge but opinion or belief, as Augustine says. But one man cannot produce certitude in another by means of the sensible signs which he proposes. For that which is in the sense faculty is less direct than that which is in the understanding, while certainty is always effected by the more direct. Therefore, one man cannot teach another.

14. The intelligible light and a species are all that are needed for knowledge. But neither of these can be caused in one man by another. For it would be necessary for a man to create something, since it seems that simple forms like these can be produced only by creation. Therefore, one man cannot cause knowledge in another and, so, cannot teach.

15. As Augustine says, nothing except God alone can give the mind of man its form. But knowledge is a form of the mind. Therefore, only God can cause knowledge in the soul.

16. just as guilt is in the mind, so is ignorance. But only God cleanses the mind of guilt, according to Isaiah (43:25): “I am he that blots out tliy iniquities for my own sake.” Therefore, God alone cleanses the mind of ignorance. And, so, only God teaches.

17. Since science is certain knowledge, one receives science from him whose words give him certainty. However, hearing a man speak does not give anyone certainty. Otherwise, anything that one person says to another would of necessity be clearly certain. Now, one reaches certitude only when he hears the truth speaking within him. And to be certain, he takes counsel with this interior voice even about those things which he hears from men. Therefore, not man but the truth speaking within, which is God, teaches.

18. No one learns through the words of another those things, which, if asked, he would have answered, even before the other spoke. But even before the teacher speaks, the pupil, upon being questioned, would answer about the matters which the teacher proposes. For he would be taught by the words of the teacher only in so far as he knew that matters were such as the teacher claimed. Therefore, one man is not taught by the words of another.

To the Contrary

11. In the second Epistle to Timothy (1:11) we read: “Wherein I am appointed a preacher... and teacher of the gentiles.” Therefore, man can be a teacher and can be called one.

2. In the second Epistle to Timothy (3:14) it is said: “But continue thou in those things which thou has learned, and which have been committed to thee.” Of this the Gloss says: “From me as from a true teacher.” We conclude as before.

3. In one place in Matthew (23:8, 9) we find: “One is your Father” and “One is your master.” But the fact that God is our Father does not make it impossible ‘for man truly to be called father. Likewise, the fact that God is our teacher does not make it impossible for man truly to be called teacher.

4. The Gloss on Romans (10:15), “How beautiful over the mountains... “ reads: “They are the feet who enlighten the Church.”“ Now, it is speaking about the Apostles. Since, then, to enlighten is the act of a teacher, it seems that men are competent to teach.

5. As is said in the Meteorology, each thing is perfect when it can generate things like itself. But scientific knowledge is a kind of perfect knowledge. Therefore, a man who has scientific knowledge can teach another.

6. Augustine says that just as the earth was watered by a fountain before the coming of sin, and after its coming needed rain froin the clouds above, so also the human mind, which is represented by the earth, was made fruitful by the fountain of truth before the coming of sin, but after its coming it needs the teaching of others as rain coming down from the clouds. Therefore, at least since sin came into the world, man is taught by man.


There is the same sort of difference of opinion on three issues: on the bringing of forms into existence, on the acquiring of virtues, and on the acquiring of scientific knowledge.

For some have said that all sensible forms come from an external agent, a separated substance or form, which they call the giver of forms or agent intelligence, and that all that lower natural agents do is prepare the matter to receive the form. Similarly, Avicenna says that our activity is not the cause of a good habit, but only keeps out its opposite and prepares us for the habit so that it may come from the substance which perfects; the souls of men. This is the agent intelligence or some similar substance.

They also hold that knowledge is caused in us only by an agent free of matter. For this reason Avicenna holds”, that the intelligible forms flow into our mind from the agent intelligence.

Some have held the opposite opinion, namely, that all three of those are embodied in things and have no external cause, but are only brought to light by external activity. For some have held that all natural forms are in act, lying hidden in matter, and that a natural agent does nothing but draw them from concealment out into the open. In like manner, some” hold that all the habits of the virtues are implanted in us by nature. And the practice of their actions removes the obstructions which, as it were, hid these habits, just as rust is removed by filing so that the brightness of the iron is brought to light. Similarly, some also have said that the knowledge of all things is con-created with the soul and that through teaching and the external helps of this type of knowledge all that happens is that the soul is prompted to recall or consider those things which it knew previously. Hence, they say that learning is nothing but remembering.

But both of these positions lack a reasonable basis. For the first opinion excludes proximate causes, attributing solely to first causes all effects which happen in lower natures. In this it derogates from the order of the universe, which is made up of the order and connection of causes, since the first cause, by the pre-eminence of its goodness, gives other beings not only their existence, but also their existence as causes. The second position, too, falls into practically the same difficulty. For, since a thing which removes an obstruction is a mover only accidentally, as is said in the Physics, if lower agents do nothing but bring things from concealment into the open,. taking away the obstructions which concealed the forms and habits of the virtues and the sciences, it follows that all lower agents act only accidentally.

Therefore, in all that has been said we ought to hold a middle position between these two, according to the teaching of Aristotle. For natural forms pre-exist in matter not actually, as some have said, but only in potency. They are brought to actuality from this state of potency through a proximate external agent, and not through the first agent alone, as one of the opinions maintains. Similarly, according to this opinion of Aristotle, before the habits of virtue are completely formed, they exist in us in certain natural inclinations, which are the beginnings of the virtues. But afterwards, through practice in their actions, they are brought to their proper completion. We must give a similar explanation of the acquisition of knowledge. For certain seeds of knowledge pre-exist in us, namely, the first concepts of understanding, which by the light of the agent intellect are immediately known through the species abstracted from sensible things. These are either complex, as axioms, or simple, as the notions of being, of the one, and so on, which the understanding grasps immediately. In these general principles, however, all the consequences are included as in certain seminal principles. When, therefore, the mind is led from these general notions to actual knowledge of the particular things, which it knew previously in general and, as it were, potentially, then one is said to acquire knowledge.

We must bear in mind, nevertheless, that in natural things something can pre-exist in potency in two ways. In one, it is in an active and completed potency, as when an intrinsic principle has sufficient power to flow into perfect act. Healing is an obvious example of this, for the sick person is restored to health by the natural power within him. The other appears in a passive potency, as happens when the internal principle does not have sufficient power to bring it into act. This is clear when air becomes fire, for this cannot result from any power existing in the air.

Therefore, when something pre-exists in active completed potency, the external agent acts only by helping the internal agent and providing it with the means by which it can enter into act. Thus, in healing the doctor assists nature, which is the principal agent, by strengthen ing nature and prescribing medicines, which nature uses as instruments for healing. On the other hand, when something pre-exists only in passive potency, then it is the external agent which is the principal cause of the transition from potency to act. Thus, fire makes actual fire of air, which is potentially fire.

Knowledge, therefore, pre-exists in the learner potentially, not, however, in the purely passive, but in the active, sense. Otherwise, man would not be able to acquire knowledge independently. Therefore, as there are two ways of being cured, that is, either through the activity of unaided nature or by nature with the aid of medicine, so also there are two ways of acquiring knowledge. In one way, natural reason by itself reaches knowledge of unknown things, and this way is called discovery; in the other way, when someone else aids the learner’s natural reason, and this is called learning by instruction.

In effects which are produced by nature and by art, art operates in the same way and through the same means as nature. For, as nature heals one who is suffering from cold by warming him, so also does the doctor. Hence, art is said to imitate nature. A similar thing takes place in acquiring knowledge. For the teacher leads the pupil to knowledge of things he does not know in the same way that one directs himself through the process of discovering something he does not know.

Now, in discovery, the procedure of anyone who arrives at the knowledge of something unknown is to apply general self-evident principles to certain definite matters, from these to proceed to particular conclusions, and from these to others. Consequently, one person is said to teach another inasmuch as, by signs, he manifests to that other the reasoning process which he himself goes through by his own natural reason. And thus, through the instrumentality, as it were, of what is told him, the natural reason of the pupil arrives at a knowledge of the things which he did not know. Therefore, just as the doctor is said to heal a patient through the activity of nature, so a man is said to cause knowledge in another through the activity of the learner’s own natural reason, and this is teaching. So, one is said to teach another and be his teacher. This is what the Philosopher means when he says: “Demonstration is a syllogism which makes someone know.”

But, if someone proposes to another things which are not included in self-evident principles, or does not make it clear that they are included, he will not cause knowledge in the other but, perhaps, opinion or faith, although even this is in some way caused by inborn first principles, for from these self-evident principles he realizes that what necessarily follows from them is to be held with certitude, and that what is contrary to them is to be rejected completely, and that assent may be given to or withheld from whatever neither follows necessarily from nor is contrary to self-evident principles. Now, the light of reason by which such principles are evident to us is implanted in us by God as a kind of reflected likeness in us of the uncreated truth. So, since all human teaching can be effective only in virtue of that light, it is obvious that God alone teaches interiorly and principally, just as nature alone heals interiorly and principally. Nevertheless, both to heal and to teach can still be used in a proper sense in the way we have explained.

Answers to Difficulties

1. Since our Lord had ordered the disciples not to be called teachers, the Gloss explains how this prohibition is to be understood, lest it be taken absolutely. For we are forbidden to call man a teacher in this sense, that we attribute to him the pre-eminence of teaching, which belongs to God. It would be as if we put our hope in the wisdom of men, and did not rather consult divine truth about those things which we hear from man. And this divine truth speaks in us through the impression of its likeness, by means of which we can judge of all things.

2. Knowledge of things is not produced in us through knowledge of signs, but through knowledge of things more certain, namely, principles. The latter are proposed to us through signs and are applied to other things which were heretofore unknown to us simply, although they were known to us in some respect, as has been said. For knowledge of principles produces in us knowledge of conclusions; knowledge of signs does not.

3. To some extent we know the things we are taught through signs, and to some extent We do not know them. Thus, if we are taught what man is, we must know something about him beforehand, namely, the meaning of animal, or of substance, or at least of being itself, which last concept cannot escape us. Similarly, if we are taught a certain conclusion, we must know beforehand what the subject and predicate are. We must also have previous knowledge of the principles through which the conclusion is taught, for “all teaching comes from pre-existing knowledge,” as is said in the Posterior Analytics. Hence, the argument does not follow.

4. Our intellect derives intelligible likenesses from sensible signs which are received in the sensitive faculty, and it uses these intelligible forms to produce in itself scientific knowledge. For the signs are not the proximate efficient cause of knowledge, but reason is, in its passage from principles to conclusions, as has been said.

5. In one who is taught, the knowledge did not exist in complete actuality, but, as it were, in seminal principles, in the sense that the universal concepts which we know naturally are, as it were, the seeds of all the knowledge which follows. But, although these seminal principles are not developed to actuality by any created power, as though they were infused by a created power, that which they have in a primitive way and virtually can develop into actuality by means of the activity of a created power.

6. We do not say that a teacher communicates knowledge to the pupil, as though the knowledge which is in the teacher is numerically the same as that which arises in the pupil. It is rather that the knowledge which arises in the pupil through teaching is similar to that which is in the teacher, and this was raised from potency into act, as has been said.

7. As the doctor is said to cause healing, although he works exteriorly, while nature alone works interiorly, so man is said to teach the truth, although he declares it exteriorly, while God teaches interiorly.

8. When Augustine proves that only God teaches, he does not intend to exclude man from teaching exteriorly, but intends to say that God alone teaches interiorly.

9. Man can truly be called a true teacher inasmuch as he teaches the truth and enlightens the mind. This does not mean, however, that he endows the mind with light, but that, as it were, he co-operates with the light of reason by supplying external help to it to reach the perfection of knowledge. This is in accordance with Ephesians (3:8-9): “To me, the least of all. the saints, is given this grace... to enlighten all men...”

10. Wisdom is twofold, created and uncreated. Man is said to be endowed with both and to improve himself by advancing in them. Uncreated wisdom, however, cannot be changed in any way, whereas in us created wisdom can be changed for some extrinsic reason, though not by reason of anything intrinsic to it. We can consider this capacity for change in two ways. In one way, according to the relation which it has to eternal things, and in this way it is entirely unchangeable. In the other, according to the existence which it has in the subject, it is changed for some extrinsic reason when the subject which has wisdom in potency is changed into a subject having it in act. For the intelligible forms in which wisdom consists are both likenesses of things and forms perfecting the understanding.

11. In the pupil, the intelligible forms of which knowledge received through teaching is constituted are caused directly by the agent intellect and mediately by the one who teaches. For the teacher sets before the pupil signs of intelligible things, and from these the agent intellect derives the intelligible likenesses and causes them to exist in the possible intellect. Hence, the words of the teacher, heard or seen in writing, have the same efficacy in causing knowledge as things which are outside the soul. For from both the agent intellect receives intelligible likenesses, although the words of the teacher are more proximately disposed to cause knowledge than things outside the soul, in so far as they are signs of intelligible forms.

12. Intellectual and bodily sight are not alike, for bodily sight is not a power which compares, so that among its objects it can proceed from one to another. Rather, all the objects of this sight can be seen as soon as it turns to them. Consequently, anyone who has the power of sight can look at all visible things, just as one who has a habit of knowledge can turn his attention to the things which he knows habitually. Therefore, the seeing subject needs no stimulus from another to see something, unless, perhaps, someone else directs the subject’s attention to some object by pointing it out or doing something of the sort.

But, since the intellective power can compare, it proceeds from some things to others. As a result, it does not have the same relation to all intelligible objects of consideration. Rather, the mind sees certain things immediately, those which are self-evident, in which are contained certain other things which it can understand only by using reason to unfold those things which are implicitly contained in principles. Thus, before the mind has the habit, it is not only in accidental potency to know these things, but also essential potency. For the mind needs a mover to actualize it through teaching, as is said in the Physics. But a man who already knew something habitually would not need this. Therefore, the teacher furnishes the pupil’s intellect with a stimulus to knowledge of the things which he teaches, as an indispensable mover, bringing the intellect from potentiality to actuality. But one who shows some thing to bodily sight prompts it to action as a nonessential mover. And one who has the habit of knowledge can in this way receive a stimulus from someone to consider something.

13. The whole certainty of scientific knowledge arises from the certainty of principles. For conclusions are known with certainty when they are reduced to the principles. Therefore, that something is known with certainty is due to the light of reason divinely implanted within us, by which God speaks within us. It comes from man, teaching from without, only in so far as, teaching us, he reduces conclusions to the principles. Nevertheless, we would not attain the certainty of scientific knowledge from this unless there were within us the certainty of the principles to which the conclusions are reduced.

14. Man, teaching from without, does not infuse the intelligible light, but he is in a certain sense a cause of the intelligible species, in so far as he offers us certain signs of intelligible likenesses, which our understanding receives from those signs and keeps within itself.

15. When it is said that nothing but God can form the mind, this is understood of its basic form, without which mind would be considered formless, no matter what other forms it had. This is the form by which it turns toward the Word and clings to Him. It is through this alone that rational nature is called formed, as is clear from Augustine.

16. Guilt is in the affections, on which only God can make an impression, as will appear later. But ignorance is in the understanding, on which even a created power can make an imprint. For the agent intellect impresses the intelligible species on the possible intellect, and through the mediation of this latter, scientific knowledge is caused in our soul by sensible things and by the teaching of man, as has been said.

17. One has the certainty of scientific knowledge, as has been said, from God alone, who has given us the fight of reason, through which we know principles. It is from these that the certainty of scientific knowledge arises. Nevertheless, scientific knowledge can in a certain sense be caused in us by man, as has been said.

18. Before the teacher speaks, the pupil would, if asked, answer about the principles through which he is taught, but not about the conclusions which someone is teaching him. Hence, he does not learn the principles from the teacher, but only the conclusions.


Q. 11: The Teacher


In the second article we ask:

Can one be called his own teacher?

[Parallel readings: S.T., I, 117, 1, ad 4. See also parallels given for preceding article.]


It seems that he can, for

1. An activity should be ascribed more to the principal cause than to the instrumental cause. But in us the agent intellect is, as it were, the principal cause of the knowledge which is produced in us. But man who teaches another is, as it were, an instrumental cause, furnishing the agent intellect with the instruments by means of which it causes knowledge. Therefore, the agent intellect is more the teacher than another man. If, then, because of what a speaker says we call him the teacher of the one who hears him, the hearer should in a much fuller sense be called his own teacher because of the light of the agent intellect.

2. One learns something only in so far as he acquires certain knowledge. But such certitude is in us by reason of the principles which are naturally known in the light of the agent intellect. Therefore, the agent intellect is especially fitted to teach. We conclude as before.

3. To teach belongs more properly to God than to man. Hence, it is said in Matthew (23:8): “For one is your master.” But God teaches us in so far as He gives us the light of reason, by means of which we can judge about everything. Therefore, we should attribute the activity of teaching especially to that light. The same conclusion follows as before.

4 It is more perfect to learn something through discovery than to learn it from another, as is clear in the Ethics. If, therefore, a man is called a teacher in virtue of that manner of acquiring knowledge by which one learns from another so that the one is called the teacher of the other, he should with much greater reason be called a teacher in virtue of the process of acquiring knowledge through discovery, and so be called his own teacher.

5. just as one is inspired to virtue by another and by himself, so also he gets to know something by discovering for himself and by learning from another. But those who attain to works of virtue without having another as an instructor or a lawgiver are said to be a law unto themselves, according to Romans (2:14): “For when the Gentiles, who have not the law, do by nature those things that are of the law... they are a law to themselves.” Therefore, the man who acquires knowledge by himself ought also to be called his own teacher.

6. The teacher is a cause of knowledge as the doctor is a cause of health, as has been said. But a doctor heals himself. Therefore, one can also teach oneself.

To the Contrary

l. The Philosopher says that it is impossible for one who is teaching to learn. For the teacher must have knowledge and the learner must not have it. Therefore, one cannot teach himself or be called his own teacher.

2. The office of teacher implies a relation of superiority, just as dominion does. But relationships of this sort cannot exist between a person and himself. For one is not his own father or master. Therefore, neither can one be called his own teacher.


Through the light of reason implanted in him and without the help of another’s instruction, one can undoubtedly acquire knowledge of many things which he does not know. This is clear with all those who acquire knowledge through discovery. Thus, in some sense one can be a cause of his own knowledge, but he cannot be called his own teacher or be said to teach himself.

For in physical reality we find two types of active principles, as is clear from the Philosopher. Now, there is one type of agent which has within itself everything which it produces in the effect, and it has these perfections in the same way as the effect, as happens in univocal agents, or in a higher way than the effect, as in equivocal causes. Then, there is a certain type of agent in which there pre-exists only a part of the effect. An example of this type is a movement which causes health, or some warm medicine, in which warmth exists either actually or virtually. But warmth is not complete health, but a part of it. The first type of agent, therefore, possesses the complete nature of action. But those of the second type do not, for a thing acts in so far as it is in act. Hence, since it actually contains the effect to be produced only partially, it is not an agent in the perfect sense.

But teaching implies the perfect activity of knowledge in the teacher or master. Hence, the teacher or master must have the knowledge which he causes in another explicitly and perfectly, as it is to be received in the one who is learning through instruction. When, however, knowledge is acquired by someone through an internal principle, that which is the active cause of the knowledge has the knowledge to be acquired only partially, that is, in the seminal principles of knowledge, which are the general principles. Therefore, properly speaking, we cannot call a man teacher or master because of such causality.

Answers to Difficulties

1. Although to some extent the agent intellect is more the principal cause than another’s teaching, the knowledge does not pre-exist in it completely, as it does in the teacher. Hence, the argument does not follow.

2. A like solution should be given to the second difficulty.

3. God knows explicitly everything which man is taught by Him. Hence, the character of teacher can suitably be applied to God. The case is not the same with the agent intellect, for the reason already given.

4. For the one learning a science, to learn it by discovery is the more perfect way of acquiring the knowledge, because it shows that he is more skillful in the acquisition of knowledge. However, for the one causing the knowledge, it is more perfect to cause it by means of instruction. For a teacher who knows the whole science explicitly can teach it to a pupil more readily than the pupil himself could learn it from his own rather general knowledge of the principles of the science.

5. A law has the same relation to matters of action as a principle has to speculative matters, but not the same as a teacher. Consequently, if he is a law unto himself, it does not follow that he can be his own teacher.

6. A doctor heals in so far as he has health, not actually, but in the knowledge of his art. But the teacher teaches in so far as he has knowledge actually. Hence, he who does not have health actually can cause health in himself because he has health in the knowledge of his art. However, it is impossible for one actually to have knowledge and not to have it, in such a way that he could teach himself.


Q. 11: The Teacher


In the third article we ask:

Can a man be taught by an angel?

[Parallel readings: II Sent., 9, 2, ad 4; C.G., III, 81; Quodl., IX, 4, 10; S.T., I, 111, 1; Q.D. de malo, 16, 12.]


It seems that he cannot, for

1. If an angel teaches, he teaches either from within or from without. But he does not teach from within, for only God can do that, Augustine says. Nor can he teach from without, as it seems, for to teach from without is to teach by means of some sensible signs, as Augustine also says. But angels do not teach us through sensible signs of this sort, unless, perhaps, they appear in a sensible form. Therefore, they do not teach us unless they so appear, an occurrence which is outside the ordinary course of nature, through a miracle, as it were.

2. It was said that angels teach us from without in some manner, inasmuch as they make an impression on our imagination.—On the contrary, a species impressed on the imagination does not suffice for actually imagining unless an intention is present, as is clear from what Augustine says. But an angel cannot bring about an intention in us, since intention is an act of will, on which only God can make an impression. Therefore, an angel cannot teach us even by making an impression on our imagination, since we cannot be taught by means of our imagination unless we actually imagine something.

3. If we are taught by angels who do not appear to us in sensible form, this can happen only if they enlighten our understanding, which, it seems, they cannot do. For they do not give it the natural light, which, since it is concreated along with the mind, is from God alone, nor the light of grace, which only God infuses. Therefore, angels cannot teach us unless they appear in visible form.

4. Whenever anyone is taught by another, the learner must examine the concepts of the teacher, so that in this way the pupil’s mind may reach science through the same reasoning process which the teacher’s mind uses. But a man cannot see the concepts of an angel. For he does not see them in themselves, just as he does not see the concepts of another man. In fact, he sees them much less since they are more unlike his own. Nor, again, does he see them in sensible signs, unless perhaps when the angels appear in sensible form, a possibility which we are not now considering. Therefore, angels are unable to teach us in any other way [that is, except by appearance in sensible form].

5. To teach us is the task of Him who “enlightens every man who comes into this world,” as appears in the Gloss on Matthew (23:8): “One is your master Christ.” But this does not refer to an angel, but only to the uncreated light, as is clear from John (1:9). Therefore.

6. Whoever teaches another leads him to the truth, and so causes truth in his soul. But only God causes truth, for, since truth is an intelligible light and a simple form, it does not come into existence gradually, and so can be produced only through creation, which is attributed to God alone. Since, therefore, angels are not creators, as Damascene says, it seems that they cannot teach.

7. An unfailing illumination can come only from an unfailing source of light, since the subject ceases to be illuminated when the light leaves. But an unfailing illumination is needed in teaching, for scientific knowledge concerns necessary things, which always exist. Therefore, teaching comes only from an unfailing light. But the light of angels is not of this kind, since their light fails unless it is divinely conserved. Therefore, an angel cannot teach.

8. In John (1:3 8), when Jesus asked: “What seek you?” the two disciples of John answered: “Rabbi, (which is to say, being interpreted, Master,) where dwellest thou?” On this the Gloss reads: “They showed their faith by this name.”Another gloss reads that He asked them not because He did not know, but that they might gain merit by their reply. And when He asked what they sought, they told Him a person, not a thing. From all this we gather that in that answer they confessed that He was a person and showed their faith by this confession. In doing, this they gained merit. But the Christian faith is worthy of merit because we acknowledge that Christ is a divine Person. Therefore, to be a teacher pertains only to a divine person.

9. Whoever teaches must disclose the truth. But, since truth is an intelligible light, it is better known to us than an angel is. Therefore, we are not taught by an angel, since that which is better known is not communicated through that which is less well known.

10. Augustine says: “Our mind is formed immediately by God without the interposition of any creature.” But an angel is a creature and, so, in the formation of the human mind does not stand between God and the human mind, as something higher than the mind and lower than God. Thus, man cannot be taught by an angel.

11. As our affections reach God Himself, so our understanding can attain to the contemplation of His essence. But God himself forms our affections directly through the infusion of grace without the mediation of an angel. Therefore, He also forms our understanding through instruction without an intermediary.

12. All knowledge takes place through some species. Therefore, if an angel is to teach a man, he has to cause in him some species through which the man will know. But he can do this only by creating the species (and an angel has no power at all to do this, as Damascene intends), or by illuminating the species which are in the phantasms, so that intelligible species may result from these in the human possible intellect. This latter seems to be a return to the error of those philosophers who make a separated substance of the agent intellect, whose task it is to illuminate the phantasms. Thus, an angel cannot teach.

13. The intellect of an angel differs more from man’s intellect than the human intellect differs from the human imagination. But the imagination cannot receive that which is in the human intellect. For the imagination can receive only particular forms, such as the intellect does not contain. Therefore, the human intellect, also, is unable to receive those forms which are in the angelic mind. And thus, man cannot be taught through an angel.

14. The light by which something is enlightened should be proportioned to the things which are illumined, as physical light is proportioned to colors. But, since angelic light is purely spiritual, there is no proportion between it and our phantasms, which are in some sense physical, inasmuch as they are retained in a bodily organ. Therefore, angels cannot teach us by illuminating our phantasms, as has been said.

15. Everything which is known is known either through its essence or through some likeness. But an angel cannot cause the knowledge through which the human mind knows things through their essence. For thus, the virtues and other things which are contained in the soul would have to be imprinted by angels, since such things are known through their essence. Similarly, angels cannot cause the knowledge of those things which are known through their likenesses, since the things to be known are closer to these likenesses which are in the knower than an angel is. Therefore, an angel can in no way cause knowledge in a man, and this is to teach.

16. As Augustine clearly shows a farmer is not called a creator even though he stimulates nature from without to produce natural effects. For equal reason, angels ought not be called teachers or masters, although they stimulate the understanding of man to acquire knowledge.

17. Since an angel is superior to man, if he teaches, his instruction must be better than human instruction. But this cannot be, for man can teach about those things which have determinate causes in nature. But angels cannot teach him about other things, such as future contingents, for the natural knowledge of the angels themselves does not extend to these things, since God alone knows such future events. Therefore, angels cannot teach men.

To the Contrary

1. Dionysius says: “I see that angels were first taught the divine mystery of the humanity of Christ, and then through them the gift of knowledge came down to us.”

2. A higher agent can do what a lower agent can, and much more nobly, as is clear from Dionysius. But the human order is lower than the angelic order. Therefore, since one man can teach another, an angel can do this with much greater reason.

3. The order of divine wisdom exists more perfectly in spiritual substances than in bodily substances. But it is part of the order of lower bodies that they receive their perfections as the result of the influence of higher bodies. Therefore, lower spirits also, namely, human spirits, receive their perfection from the influence of higher spirits, that is to say, angels.

4. Everything which is in potentiality can be developed to actuality through that which is in actuality; and that which is less in actuality can be developed through that which is more completely in actuality. But the angelic intellect is more in actuality than the human intellect. Therefore, the human intellect can be developed to the actuality of knowledge through the angelic intellect. And thus an angel can teach man.

5. Augustine says that some receive the doctrine of salvation directly from God, some from an angel, and some from man. Therefore, not only God but angels and men teach.

6. That which shines its light, as the sun, and one who opens a window which obstructed the light, are both said to illuminate the house. But, although only God infuses the light of truth into the mind, an angel or a man can remove something which prevented perception of light. Therefore, not only God but an angel or a man can teach.


An angel influences a man in two ways. In one way the action follows our way of acting, when, for instance, an angel appears to man in a sensible form, either taking on a body or in some other way, and instructs the man by means of sensible speech. We are not now investigating angelic teaching of this sort, for in this way an angel teaches no differently than a man does. The other way in which an angel influences us is the angelic way of acting, that is, invisibly. The purpose of this investigation is to find out how man can be taught in this way by an angel.

We must bear in mind that, since an angel is between God and man, due order requires that he should have an intermediate mode of teaching, lower than God’s but higher than man’s. We can see in what sense this is true only if we see how God teaches and how man teaches.

To show this we must bear in mind that there is this difference between understanding and bodily sight, namely, that, for the purposes of knowing, all the objects of bodily sight are equally near to it. For a sense is not a power which compares, so that it has to reach one of its objects by means of another. But, for the purposes of knowing, all intelligible things are not equally near to the intellect. Rather, some can be seen immediately, and some can be seen only by examining

other principles. Therefore, man gains knowledge of things he does not know through two things: intellectual light and self-evident primary concepts. The latter have the same relation to the intellectual light of the agent intellect as tools to the craftsman.

Now, God in a most excellent way causes man’s knowledge in both of these ways. For He adorned the soul itself with intellectual light and imprinted on it the concepts of the first principles, which are, as it were, the sciences in embryo, just as He impressed on other physical things the seminal principles for producing all their effects.

But, since in the order of nature each man shares equally in the specific nature of intellectual light, he cannot in any way be the cause of knowledge in another by causing or increasing that light in him. But he does in a sense cause knowledge in another man as regards the new knowledge which is caused by self-evident principles. He does this, not as one who gives knowledge of the principles, but as one who shows certain sensible signs to the external senses, and thus brings into actuality that which was contained in the principles implicitly and in a certain sense in potentiality, as was said above.

But, since by nature an angel has intellectual light more perfectly than man, he can cause man to know in both ways, in a manner lower than God, but higher than man. For, as regards the light, although he cannot infuse the intellectual light, as God does, he can strengthen the infused light to make man see more perfectly. For that which is imperfect in a given genus has its power intensified when it is brought in contact with that which is more perfect in that genus. Thus, in bodies, we see that the body which is given position is strengthened by the body giving it position, which is related to it as actuality to potentiality, as is said in the Physics.

As regards principles, too, an angel can teach a man, not, it is true, by giving him knowledge of the principles, as God does, nor by proposing to him under sensible signs the manner in which the conclusions are deduced from the principles, as man does, but by forming in his imagination certain species which can be formed by stimulating the corporeal organ. This is clearly what happens with persons sleeping and with the insane, who experience different phantasms according to the diversity of vapors which rise to the head. And in this way, by means of contact with another spirit, it is possible for an angel to use images of this sort to show what he himself knows to the person with whom he has come in contact, as Augustine says.

Answers to Difficulties

1. An angel who teaches invisibly teaches interiorly, it is true, in comparison with the instruction of a man who proposes his instruction to the external senses. But in comparison with the teaching of God, who works within the mind by infusing light, the teaching of an angel is classed as external.

2. Although an intention of the will cannot be forced, still an intention of the sensitive part can be forced. For just as, when someone is pricked, he has to pay attention (intendere) to the hurt, so, too, with all the other sensitive powers which use a bodily organ. And this attention (intentio) is enough for the imagination.

3. An angel does not infuse the light of grace or the light of nature, but strengthens the divinely infused light of nature, as has been said.

4. As in physical things there is an univocal agent, which imprints a form in the same way it has it, and an equivocal agent, which has it in a way different from that in which it imprints it, so also in teaching. For one man teaches another as a kind of univocal agent, and thus communicates knowledge to the other in the same way that he himself has it, by proceeding from causes to the effects. It is for this reason that the concepts of the teacher must be conveyed to the learner through some signs. But an angel teaches as a kind of equivocal cause, for he knows intuitively that which man learns through a process of reasoning. Hence, an angel does not teach a man in such a way that the concepts of the angel are disclosed to the man, but the result is rather this, that the man is made to know in his own way those things which the angel knows in a far different way.

5. Our Lord is speaking of that kind of teaching which befits God alone, as is clear from the Gloss on this passage. We do not ascribe this kind of teaching to an angel.

6. He who teaches does not cause the truth, but knowledge of the truth, in the learner. For the propositions which are taught are true before they are known, since truth does not depend on our knowledge of it, but on the existence of things.

7. Although the knowledge which we get through teaching may be concerned with things that do not cease to be, the knowledge itself can cease to be. Hence, it is not necessary for the illumination of teaching to come from an unfailing light. Or, if it is from an unfailing light as its first principle, this does not entirely exclude a created light capable of failing, from being able to exist as a mediate principle.

8. A certain progression in faith appears in the disciples of Christ, so that at first they respected Him as a wise man and a teacher, and later listened to Him as God teaching them. Hence, a gloss a little further on says: “Since Nathanael knew that Christ, though absent, saw what he had done in another place, which is a sign of the Godhead, he acknowledged that Christ was not only a teacher, but also the Son of God.

9. An angel does not make an unknown truth appear by manifesting its own substance, but by proposing another truth better known, or by strengthening the light of the understanding. Hence, the argument does not follow.

10. It is not Augustine’s intention to say that the nature of the angelic mind is not more excellent than that of the human mind, but that angels are not between God and the human mind in such a way that the human mind receives the ultimate form of its perfection by being united to an angel, as some have held. They say that the final beatitude of man consists in this, that our understanding is united to an intelligence whose beatitude is union with God Himself.

11. There are in us some powers which are constrained by their subject and object, as the sensitive powers, which are stimulated both by excitation of the organ and by the strength of their object. But our understanding is not constrained by its subject, since it does not use a bodily organ. Rather, it is constrained by its object, because the effectiveness of a demonstration forces one to assent to a conclusion. However, the affections are constrained neither by their subject nor their object, but move toward one thing or another by reason of their own inclination. Hence, only God, who acts interiorly, can make an impression on the affections. But a man or an angel can, to a certain extent, make an impression on our understanding by representing to the mind the objects by which our understanding is constrained.

12. An angel does not create the species in our mind nor directly illuminate the phantasms. But our understanding can more effectively enlighten phantasms when an angelic light is united to the light of our understanding. Even if an angel did immediately illuminate the phantasms, it still would not follow from this that the opinion of those philosophers would be true. For, although it is the task of the agent intellect to illuminate the phantasms, it could still be said that this is not a function which belongs to it alone.

13. The imagination can receive those things which are in the human understanding, but in a different manner. Similarly, the human understanding in its own manner can receive those things which are in the angelic understanding. But, although the human understanding is more like the imagination by reason of their common subject in so far as both are powers of the one soul, it is more like the angelic intellect by reason of their common genus, for both are immaterial powers.

14. There is nothing to prevent something spiritual from being capable of exercising an influence on something physical, for nothing prevents things which are lower from being acted upon by things which are higher.

15. An angel is not the cause of man's knowledge in so far as a man knows things through their essence, but in so far as he knows things through their likenesses. This does not mean that an angel is closer to things than their likenesses are, but that he makes the likenesses of things appear in the mind either by moving the imagination or strengthening the light of understanding.

16. To create implies first causality, which belongs to God alone; to make implies causality in general; to teach implies the same general causality with reference to knowledge. Thus, only God is called Creator, but God, angels, and men can be called makers and teachers.

17. Just as an angel knows more than man, even about those things which have determinate causes in nature, so he can teach more than man. And the things which an angel does teach he can teach in a more excellent way. Hence, the argument does not follow.


Q. 11: The Teacher


In the fourth article we ask:

Is teaching an activity of the contemplative or the active life?

[Parallel readings: III Sent., 35, 1, 3, sol. 1, ad 3; S.T., II-II, 181, 3; Contra retrahentes a religionis ingressu, c. 7, ad 7.]


It seems to be an activity of the contemplative life, for

1. “There is no active life where there is no body,” as Gregory says. But there is teaching where there is no body, for even angels, who have no bodies, teach, as has been said. Therefore, it seems that teaching pertains to the contemplative life.

2. Gregory says: “One engages in the active life in order to arrive at the contemplative later.” But teaching does not precede contemplation, but follows it. Therefore, teaching does not pertain to the active life.

3. Gregory also says that the active life “sees less while it is engaged in work.” But one who teaches must of necessity see more than one who simply contemplates. Therefore, teaching pertains more to the contemplative than to the active life.

4. It is the same perfection which makes each thing perfect in itself and enables it to give others a perfection like its own. Thus it is by reason of one and the same warmth that fire itself is warm and gives warmth to other things. But one's own perfection in meditation on things of God belongs to the contemplative life. Therefore, teaching, which is the communication of this same perfection to another, belongs to the contemplative life.

5. The active life is occupied with temporal things. But teaching is occupied mainly with things eternal, for the teaching of these latter is more excellent and more perfect. Therefore, teaching does not pertain to the active, but to the contemplative life.

To the Contrary

1. Gregory says: “The active life consists in giving bread to the hungry, and in teaching the ignorant the word of wisdom.”

2. The works of mercy are part of the active life. But teaching is counted among the spiritual works of mercy. Therefore, it is part of the active life.


The contemplative and the active life are distinguished from each other by their subject matter and that to which they are ordained. For the subject matter of the active life is temporal affairs, with which human acts are concerned. But the intelligible natures of things, on which the one contemplating meditates, are the subject matter of the contemplative life. This diversity of subject matter arises from a diversity of the end to be attained, just as in all other things the requirements of the end to be attained prescribe certain conditions in the subject matter.

For the end toward which the contemplative life, as we are now examining it, is ordained is the consideration of truth, of that truth, I say, which is uncreated, considered in the manner possible to the one contemplating it. We see this truth imperfectly in this life, but perfectly in the life to come. Hence, Gregory says6 that the contemplative life begins here in order to be made perfect in the life to come. But the end toward which the active life is directed is the activity which is directed to the help of our neighbor.

Moreover, in the act of teaching we find a twofold subject matter, and as an indication of this, two accusatives are used as objects of the verb which expresses the act of teaching. This is so because the subject which one teaches is one kind of subject matter of teaching, and the one to whom the knowledge is communicated is another type of subject of teaching. Accordingly, by reason of the former, teaching pertains to the contemplative life, but by reason of the latter it is part of the active life. But, if we consider the end toward which it is directed, teaching seems to be a part only of the active life, because its last subject matter, in which it reaches the end proposed to it, is a subject with which the active life is concerned. Therefore, although it is in some sense a function of the contemplative life, as is clear from what has been said, it is, more properly a work of the active than of the contemplative life.

Answers to Difficulties

1. There is no active life where there is no body, inasmuch as toil is connected with its exercise, and inasmuch as it relieves the infirmities of our neighbors. It is in this sense that Gregory says: “The active life is laborious because it works in the sweat of its brow; two things which will not be in the future life.” Nevertheless, there is still hierarchical activity among the heavenly spirits, as Dionysius says, and the manner of the activity is different from the active life which we now lead in this life. Hence, the teaching which will exist there is far different from the teaching here.

2. As Gregory says: “Just as the good disposal of our life leads us to try to pass from the active life to the contemplative, in like manner the minds of many can usefully turn back from the contemplative to the active life so that the flame which the coutemplative life has enkindled in their minds may lead them to live the active life more perfectly.” Still, we must bear in mind that the active life precedes the contemplative in regard to those acts which have a subject matter in which the contemplative life has no part at all, but the active life must follow the contemplative in those acts which receive their subject matter from the contemplative life.

3. The insight of the teacher is a source of teaching, but teaching itself consists more in the communication of the things seen than in the vision of them. Hence, the insight of the teacher belongs more to action than to contemplation.

4. This argument proves that the contemplative life is a source of teaching just as heat is the source of the act of warming, and is not itself that activity. For we see that the contemplative life is the source of the active life in so far as it directs it, just as, conversely, the active life disposes for the contemplative.

5. The solution is clear from what has been said, for teaching and the contemplative life have the first type of subject matter in common, as has been said above.