Thomas Aquinas

“ I answer that, 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 ”

“ 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. ”

“ 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. ”

“ Further, the human body is nobler than other inferior bodies. But by the apprehension of the human soul the human body is changed to heat and cold, as appears when a man is angry or afraid: indeed this change sometimes goes so far as to bring on sickness and death. Much more, then, can the human soul by its power change corporeal matter. ”

“ If of things that he knows, he to whom these signs are proposed is already in the possession of knowledge, and does not acquire it from the master. If they are signs of things that he does not know, he can learn nothing therefrom: for instance, if one were to speak Greek to a man who only knows Latin, he would learn nothing thereby. ”

“ Further, if one man teaches another this is only inasmuch as he acts through his own knowledge, so as to cause knowledge in the other. But a quality through which anyone acts so as to produce his like, is an active quality. Therefore it follows that knowledge is an active quality just as heat is. ”

“ There are certain spiritual substances whose powers are not determinate to certain bodies; such are the angels who are naturally unfettered by a body; consequently various bodies may obey them as to movement. ”

“ Certain men in this state of life are greater than certain angels, not actually, but virtually; forasmuch as they have such great charity that they can merit a higher degree of beatitude than that possessed by certain angels. In the same way we might say that the seed of a great tree is virtually greater than a small tree, though actually it is much smaller.
Art. 3 - Whether man by the power of his soul can change corporeal matter? Objection 1: It would seem that man by the power of his soul can change corporeal matter. ”

“ 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 ”