The Malleus Maleficarum by Kramer and Sprenger, 1489, Excerpts
There are, as it is said in the Papal Bull, seven methods by which they infect with witchcraft the venereal act and the conception of the womb: First, by inclining the minds of men to inordinate passion; second, by obstructing their generative force; third, by removing the members accommodated to that act; fourth, by changing men into beasts by their magic art; fifth, by destroying the generative force in women; sixth, by procuring abortion; seventh, by offering children to devils, besides other animals and fruits of the earth with which they work much harm.
These women satisfy their filthy lusts not only in themselves, but even in the mighty ones of the age, of whatever state and condition; causing by all sorts of witchcraft the death of their souls through the excessive infatuation of carnal love, in such a way that for no shame or persuasion can they desist from such acts. And through such men, since witches will not permit any harm to come to them either from themselves or from others once they have them in their power, there arises the great danger of the time, namely, the extermination of the Faith. And in this way do witches every day increase.
The devil, being a spirit, has power over a corporeal creature to cause or prevent a local motion. He can directly prevent the erection of that member which is adapted to fructification, just as he can prevent local motion. He can prevent the flow of the vital essence to the members in which lie the motive power; by closing as it were the seminary ducts, so that it does not descend to the generative channels, or falls back from them, or does not project from them, or in any of many ways fails in its function.
When the member is in no way stirred, and can never perform the act of coition, this is a sign of frigidity of nature; but when it is stirred and becomes erect, but yet cannot perform, it is a sign of witchcraft.
God allows more power of witchcraft over the genital functions, on account of the first corruption of sin which came to us from the act of generation, so also He allows greater power over the actual genital organ, even to its removal.
Elvira Mistress of the Dark