REGARDING the method by which they impede the act of procreation both in humans and in domestic animals of both sexes, the reader can inform himself from the discussion above in the question as to whether demons are able to turn the minds of humans to love or hatred. There, after the solutions to the arguments, a specific explanation is given regarding the methods by they are able to impede the force of procreation with God's permission. In this regard it should be noted that such an impediment is carried out in two ways, from within and from without. It is done from within in two ways. In the first, they directly suppress the hardness of the member appropriate for propagation (this should not be viewed as impossible, since in other ways they are able to impede the natural motion in any limb). In the second, they prevent the sending of spirits to the limbs in which the power of motion resides, by cutting off the seed's paths, as it were, so that it cannot descend to the vessels of procreation or be separated out or sent forth. Externally, they sometimes cause this through images or as the result of eating plants, sometimes through other external objects, like the testicles of roosters or the eating of plants.

It should not be believed that a man is rendered impotent through the virtue of these things. Instead, with the demons' hidden virtue, which makes an illusion, the sorceresses can affect the force of procreation with sorcery by means of such things, preventing a man from being able to couple or a woman from being able to conceive. The reason for this is that God gives permission more in connection with this act, which is the one through which the first sin is spread, than with other human acts. This is also the case with snakes, which are more useful for incantations than are other animals, and as a result it has frequently been found by us and other inquisitors that they used snakes and snakeskins to inflict such impediments.