When I first set out to write stories about incubi, succubi, and vampires, all I really knew about them was that they were mythological beings known for ravishing humans—a good premise, I thought, for a series of scalding erotic romances. Being an obsessive-compulsive researcher, I read everything I could find on the subject in order to build a world for my characters: a Babylonian succubus, a brooding djinni, a cheerfully lusty satyr, a tall, babe-alicious Nordic elf, and the occasional bothersome bloodsucker. It turns out that, until fairly recently, most people, no matter how learned, regarded “sexual demons” as real (in fact, a surprising number still do).
St. Augustine (354-430) wrote that “…sylvans and fauns, who are commonly called ‘incubi,’ had often made wicked assaults upon women, and satisfied their lust upon them.” Nine hundred years later, St. Thomas Aquinas explained that incubi could actually beget human beings, “not from the seed of such demons… but from the seed of men taken for the purpose; as when the demon assumes first the form of a woman, and afterwards of a man.” Hmm… Digging deeper, I found a 17th century treatise by Father Ludovicus Maria Sinistrari de Ameno, in which he described in salacious detail how an incubus, having morphed into a female succubus, will ravish “ardent, robust men” for the purpose of capturing their high-test seed. (Nice work if you can get it.) After turning back into a male, he targets “women of a like constitution, with whom the incubus copulates, taking care that both shall enjoy a more than normal orgasm…”
I am not making this up.