The Malleus Maleficarum by Kramer and Sprenger, 1489, Excerpts
It is common to all of them to practise carnal copulation with devils.
As to the method in which witches copulate with Incubus devils, six points are to be noted. First, as to the devil and the body which he assumes, of what element it is formed. Second, as to the act, whether it is always accompanied with the injection of semen received from some other man. Third, as to the time and place, whether one time is more favourable than another for this practice. Fourth, whether the act is visible to the women, and whether only those who were begotten in this way are so visited by devils. Fifth, whether it applies only to those who were offered to the devil at birth by midwives. Sixth, whether the actual venereal pleasure is greater or less in this act.
But with regard to any bystanders, the witches themselves have often been seen lying on their backs in the fields or the woods, naked up to the very navel, and it has been apparent from the disposition of those limbs and members which pertain to the venereal act and orgasm, as also from the agitation of their legs and thighs, that, all invisibly to the bystanders, they have been copulating with Incubus devils; yet sometimes, howbeit this is rare, at the end of the act a very black vapour, of about the stature of a man, rises up into the air from the witch.
These Incubus devils will not only infest those women who have been generated by means of such abominations, or those who have been offered to them by midwives, but that they try with all their might, by means of witches who are bawds or hot whores, to seduce all the devout and chaste maidens in that whole district or town.