But an opposite opinion holds that the devil cannot so easily and readily do harm by himself to mankind, as he can harm them through the instrumentality of witches, although they are his servants. In the first place we may consider the act of generation. But for every act which has an effect upon another some kind of contact must be established, and because the devil, who is a spirit, can have no such actual contact with a human body, since there is nothing common of this kind between them, therefore he uses some human instruments, and upon these he bestows the power of hurting by bodily touch. And many hold this to be proven by the text, and the gloss upon the text, in the 3rd chapter of S. Paul’s Epistle to the Galatians:118 O senseless Galatians, who hath bewitched you that you should not obey the truth? And the gloss upon this passage refers to those who have singularly fiery and baleful eyes, who by a mere look can harm others, especially young children. And Avicenna119 also bears this out, Naturalism, Book 3, c. the last, when he says; “Very often the soul may have as much influence upon the body of another to the same extent as it has upon its own body, for such is the influence of the eyes of anyone who by his glance attracts and fascinates another.” And the same opinion is maintained by al-Gazali120 in the 5th book and 10th c. of his Physics. Avicenna also suggests, although he does not put this opinion forward as irrefutable, that the power of the imagination can actually change or seem to change extraneous bodies, in cases where the power of the imagination is too unrestrained; and hence we gather that the power of the imagination is not to be considered as distinct from a man’s other sensible powers, since it is common to them all, but to some extent it includes all those other powers. And this is true, because such a power of the imagination can change adjacent bodies, as, for example, when a man is able to walk along some narrow beam which is stretched down the middle of a street. But yet if this beam were suspended over deep water he would not dare to walk along it, because his imagination would most strongly impress upon his mind the idea of falling, and therefore his body and the power of his limbs would not obey his imagination, and they would not obey the contrary thereto, that is to say, walking directly and without hesitation. This change may be compared to the influence exercised by the eyes of a person who has such influence, and so a mental change is brought about although there is not any actual and bodily change.
Moreover, if it be argued that such a change is caused by a living body owing to the influence of the mind upon some other living body, this answer may be given. In the presence of a murderer blood flows from the wounds in the corpse of the person he has slain. Therefore without any mental powers bodies can produce wonderful effects, and so a living man if he pass by near the corpse of a murdered man, although he may not be aware of the dead body, is often seized with fear.
Again, there are some things in nature which have certain hidden powers, the reason for which man does not know; such, for example, is the lodestone, which attracts steel and many other such things, which S. Augustine mentions in the 20th book Of the City of God.
And so women in order to bring about changes in the bodies of others sometimes make use of certain things, which exceed our knowledge, but this is without any aid from the devil. And because these remedies are mysterious we must not therefore ascribe them to the power of the devil as we should ascribe evil spells wrought by witches.
Moreover, witches use certain images and other strange periapts, which they are wont to place under the lintels of the doors of houses, or in those meadows where flocks are herding, or even where men congregate, and thus they cast spells over their victims, who have ofttimes been known to die. But because such extraordinary effects can proceed from these images it would appear that the influence of these images is in proportion to the influence of the stars over human bodies, for as natural bodies are influenced by heavenly bodies, so may artificial bodies likewise be thus influenced. But natural bodies may find the benefit of certain secret but good influences. Therefore artificial bodies may receive such influence. Hence it is plain that those who perform works of healing may well perform them by means of such good influences, and this has no connection at all
