(CG 3/102). That God alone works Miracles (Book 3. God, the End of Creatures) (Summa Contra Gentiles) (Aquinas, Thomas, St.)

IT was the theory of Avicenna that matter is far more obedient to spiritual agencies than to the action of contraries in nature. Hence he goes on to say that upon the suggestion of these spiritual agents there sometimes follows an effect in the lower world, such as rain, or the cure of some sick person, without the coming in of any intermediate corporeal agency. He instances the change wrought in the body by the mere suggestion of a strong impression of phantasy, as when one walking upon a plank set aloft easily falls, because his fear pictures a fall to him, whereas he would not fall if the same plank were laid on the ground, giving him no occasion to fear. Again it is notorious that upon the mere suggestion of the soul the body grows hot, as in desire or anger, or is chilled, as in fear. Sometimes too a strong suggestion brings on an illness, a fever, or even leprosy. Thereupon Avicenna says that if the soul is pure, not subject to bodily passions, and strong in its suggestive power, not only its own body will obey its suggestion, but even foreign bodies, even to the healing of the sick upon suggestion made by it. And this he thought to be the cause of the evil eye (fascinationis), that any soul having a strong affection of malevolence is capable of making a noxious impression on another, particularly on a child, who for the tenderness of his constitution is readily susceptible of such impressions. Hence he concludes that much more does an effect in this lower world follow upon the suggestion of pure spirits, without the action of any bodily agent. And this position tallies well enough with his other theories: for he supposes that all substantial forms in this lower world are effluxes from a pure spirit, and that bodily agents do no more than prepare the matter to receive the impression of the separately subsisting spiritual agent. But this is not true according to the doctrine of Aristotle, who proves that such forms as are in matter arise from other forms which are also in matter, for thus is maintained the likeness between maker and made.

The fact is, a created spirit has no power of its own to induce any form upon corporeal matter otherwise than by setting some body into local motion. This much is in the power of a created spirit, to make a body obey it to the extent of moving locally. So by moving a body locally an angel can employ natural agents to the production of certain effects. But such action is not miraculous, properly speaking. Hence it remains true that created spirits do not work miracles of their own power. But there is nothing against their working miracles inasmuch as they work in the power of God, as appears from the fact that one choir of angels is especially told off, as Gregory says, to work miracles. Gregory further says that some saints sometimes work miracles by an act of power, and not merely by intercession.