Of Things Pertaining to the Action of Man

Of Things Pertaining to the Action of Man — St. Thomas Aquinas asks: Whether one man can teach another?; Whether man can teach the angels?; Whether man by the power of his soul can change corporeal matter?; Whether the separate human soul can move bodies at least locally?.

We have next to consider those things which pertain to the action of man, who is composed of a created corporeal and spiritual nature. In the first place we shall consider that action (in general) and secondly in regard to the propagation of man from man. As to the first, there are four points of inquiry:

Article 1: Whether one man can teach another?

The Apostle says (1 Tim. 2:7): "Whereunto I am appointed a preacher and an apostle . . . a doctor of the Gentiles in faith and truth."

On this question there have been various opinions. For Averroes, commenting on De Anima iii, maintains that all men have one passive intellect in common, as stated above (). From this it follows that the same intelligible species belong to all men. Consequently he held that one man does not cause another to have a knowledge distinct from that which he has himself; but that he communicates the identical knowledge which he has himself, by moving him to order rightly the phantasms in his soul, so that they be rightly disposed for intelligible apprehension. This opinion is true so far as knowledge is the same in disciple and master, if we consider the identity of the thing known: for the same objective truth is known by both of them. But so far as he maintains that all men have but one passive intellect, and the same intelligible species, differing only as to various phantasms, his opinion is false, as stated above ().

Besides this, there is the opinion of the Platonists, who held that our souls are possessed of knowledge from the very beginning, through the participation of separate forms, as stated above (); but that the soul is hindered, through its union with the body, from the free consideration of those things which it knows. According to this, the disciple does not acquire fresh knowledge from his master, but is roused by him to consider what he knows; so that to learn would be nothing else than to remember. In the same way they held that natural agents only dispose (matter) to receive forms, which matter acquires by a participation of separate substances. But against this we have proved above (; ) that the passive intellect of the human soul is in pure potentiality to intelligible (species), as Aristotle says (De Anima iii, 4).

We must therefore decide the question differently, by saying that the teacher causes knowledge in the learner, by reducing him from potentiality to act, as the Philosopher says (Phys. viii, 4). In order to make this clear, we must observe that of effects proceeding from an exterior principle, some proceed from the exterior principle alone; as the form of a house is caused to be in matter by art alone: whereas other effects proceed sometimes from an exterior principle, sometimes from an interior principle: thus health is caused in a sick man, sometimes by an exterior principle, namely by the medical art, sometimes by an interior principle as when a man is healed by the force of nature. In these latter effects two things must be noticed. First, that art in its work imitates nature for just as nature heals a man by alteration, digestion, rejection of the matter that caused the sickness, so does art. Secondly, we must remark that the exterior principle, art, acts, not as principal agent, but as helping the principal agent, but as helping the principal agent, which is the interior principle, by strengthening it, and by furnishing it with instruments and assistance, of which the interior principle makes use in producing the effect. Thus the physician strengthens nature, and employs food and medicine, of which nature makes use for the intended end.

Now knowledge is acquired in man, both from an interior principle, as is clear in one who procures knowledge by his own research; and from an exterior principle, as is clear in one who learns (by instruction). For in every man there is a certain principle of knowledge, namely the light of the active intellect, through which certain universal principles of all the sciences are naturally understood as soon as proposed to the intellect. Now when anyone applies these universal principles to certain particular things, the memory or experience of which he acquires through the senses; then by his own research advancing from the known to the unknown, he obtains knowledge of what he knew not before. Wherefore anyone who teaches, leads the disciple from things known by the latter, to the knowledge of things previously unknown to him; according to what the Philosopher says (Poster. i, 1): "All teaching and all learning proceed from previous knowledge."

Now the master leads the disciple from things known to knowledge of the unknown, in a twofold manner. Firstly, by proposing to him certain helps or means of instruction, which his intellect can use for the acquisition of science: for instance, he may put before him certain less universal propositions, of which nevertheless the disciple is able to judge from previous knowledge: or he may propose to him some sensible examples, either by way of likeness or of opposition, or something of the sort, from which the intellect of the learner is led to the knowledge of truth previously unknown. Secondly, by strengthening the intellect of the learner; not, indeed, by some active power as of a higher nature, as explained above (; ) of the angelic enlightenment, because all human intellects are of one grade in the natural order; but inasmuch as he proposes to the disciple the order of principles to conclusions, by reason of his not having sufficient collating power to be able to draw the conclusions from the principles. Hence the Philosopher says (Poster. i, 2) that "a demonstration is a syllogism that causes knowledge." In this way a demonstrator causes his hearer to know.

Article 2: Whether man can teach the angels?

Dionysius says (Div. Nom. iv) that every Divine enlightenment to the superior angels, by making their thoughts known to them; but concerning Divine things superior angels are never enlightened by inferior angels. Now it is manifest that in the same way as inferior angels are subject to the superior, the highest men are subject even to the lowest angels. This is clear from Our Lord's words (Mat. 11:11): "There hath not risen among them that are born of woman a greater than John the Baptist; yet he that is lesser in the kingdom of heaven is greater than he." Therefore angels are never enlightened by men concerning Divine things. But men can by means of speech make known to angels the thoughts of their hearts: because it belongs to God alone to know the heart's secrets.

Article 3: Whether man by the power of his soul can change corporeal matter?

Augustine says (De Trin. iii, 8): "Corporeal matter obeys God alone at will."

As stated above (), corporeal matter is not changed to (the reception of) a form save either by some agent composed of matter and form, or by God Himself, in whom both matter and form pre-exist virtually, as in the primordial cause of both. Wherefore of the angels also we have stated () that they cannot change corporeal matter by their natural power, except by employing corporeal agents for the production of certain effects. Much less therefore can the soul, by its natural power, change corporeal matter, except by means of bodies.

Article 4: Whether the separate human soul can move bodies at least locally?

the Philosopher says (De Anima i, 3) that the soul cannot move any other body whatsoever but its own.

The separate soul cannot by its natural power move a body. For it is manifest that, even while the soul is united to the body, it does not move the body except as endowed with life: so that if one of the members become lifeless, it does not obey the soul as to local motion. Now it is also manifest that no body is quickened by the separate soul. Therefore within the limits of its natural power the separate soul cannot command the obedience of a body; though, by the power of God, it can exceed those limits.