Incubus. The name given by demonographers to a demon when it takes on the appearance of a man in order to have relations with a woman.

Delrio, in addressing this topic, makes the initial and incontrovertible point that witches have the practice of having carnal relations with demons and strongly attackes Chytree, Wyer, Biermann and Godelman for having a contrary opinion, as well as Cardan and Jean-Baptiste Porta who regarded these relations as purely illusory.

It is true that St. Justin, martyr, Clement of Alexandria, Tertullien, St. Cyprian, St. Augustine and St. Jerome thought that this type of relations were possible, but that from the possibility to the reality was a great distance. Delrio shows that this is possible, because the demons could take on a life-like and fantastic body and its limbs to a certain extent. As for the seed necessary for the consummation of the sexual act, he adds that the demons could subtly remove some from men during their nocturnal emissions or otherwise, and imitate ejaculation into the womb: from which he concludes that the incubi could sire, though not from their own nature, since they are but spirits, but because the seed that they had removed kept enough vital spirit and warmth to be effective in impregnating the woman.

To back up this belief, the author seriously cites what the Platonists thought about the relations between men and genies; what the Poets said about the birth of the demi-gods, such as Aeneas or Sarpedon and what our old tales tell about the sorcerer Merlin. These feats of sorcery, that he always accepted, also support him. One can judge by the solidity of his proofs, of whose opinion he follows, and the readings that can be seen throughout the author’s disquisitions magiques , Bk. II, Question 15, P. 159 ff.

It is more reasonable to think that all that is known of incubi , even including the statements of witches, is the result of an ardent imagination and a fiery temperament. From women abandoned to the deprivations of their heart, aflame with impure desires, having dreams and hallucinations and believing that they had relations with demons, there is nothing there so stunning in imagining being transported through the air on a broom stick, dancing, feasting, adoring the “goat,” and having relations with him or with his henchmen. All these things, however, happen beyond the plane of the senses, rather they are the effects of a vivid imagination; it requires only the least bit more effort to suppose that incubi exist.