Objection 1: It would seem that man by the power of his soul can change corporeal matter. For Gregory says (Dialog. ii, 30): "Saints work miracles sometimes by prayer, sometimes by their power: thus Peter, by prayer, raised the dead Tabitha to life, and by his reproof delivered to death the lying Ananias and Saphira." But in the working of miracles a change is wrought in corporeal matter. Therefore men, by the power of the soul, can change corporeal matter.
Obj. 2: Further, on these words (Gal. 3:1): "Who hath bewitched you, that you should not obey the truth?" the gloss says that "some have blazing eyes, who by a single look bewitch others, especially children." But this would not be unless the power of the soul could change corporeal matter. Therefore man can change corporeal matter by the power of his soul.
Obj. 3: 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.
On the contrary, Augustine says (De Trin. iii, 8): "Corporeal matter obeys God alone at will."
I answer that, As stated above (Q. 110, A. 2), 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 (Q. 110, A. 2) 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.
Reply Obj. 1: The saints are said to work miracles by the power of grace, not of nature. This is clear from what Gregory says in the same place: "Those who are sons of God, in power, as John says--what wonder is there that they should work miracles by that power?"
Reply Obj. 2: Avicenna assigns the cause of bewitchment to the fact that corporeal matter has a natural tendency to obey spiritual substance rather than natural contrary agents. Therefore when the soul is of strong imagination, it can change corporeal matter. This he says is the cause of the "evil eye."
But it has been shown above (Q. 110, A. 2) that corporeal matter does not obey spiritual substances at will, but the Creator alone. Therefore it is better to say, that by a strong imagination the (corporeal) spirits of the body united to that soul are changed, which change in the spirits takes place especially in the eyes, to which the more subtle spirits can reach. And the eyes infect the air which is in contact with them to a certain distance: in the same way as a new and clear mirror contracts a tarnish from the look of a "menstruata," as Aristotle says (De Somn. et Vigil.; [*De Insomniis ii]).
Hence then when a soul is vehemently moved to wickedness, as occurs mostly in little old women, according to the above explanation, the countenance becomes venomous and hurtful, especially to children, who have a tender and most impressionable body. It is also possible that by God's permission, or from some hidden deed, the spiteful demons co-operate in this, as the witches may have some compact with them.
Reply Obj. 3: The soul is united to the body as its form; and the sensitive appetite, which obeys the reason in a certain way, as stated above (Q. 81, A. 3), it is the act of a corporeal organ. Therefore at the apprehension of the human soul, the sensitive appetite must needs be moved with an accompanying corporeal operation. But the apprehension of the human soul does not suffice to work a change in exterior bodies, except by means of a change in the body united to it, as stated above (ad 2).