An incubus (plural incubi) is a demon in male form supposed to lie upon sleepers, especially women, in order to have sexual intercourse with them, according to a number of mythological and legendary traditions. Its female counterpart is the succubus. An incubus may pursue sexual relations with a woman in order to father a child, as in the legend of Merlin, and some sources indicate that it may be identified by its unnaturally cold penis. Religious tradition holds that repeated intercourse with an incubus or succubus may result in the deterioration of health, or even death.
The word is derived from the Latin preposition in, which in this case means on top of, and cubo, which is Latin for "I lie". The word incubo translates into "I lie on top".
A number of rational explanations have been offered for the origin of the incubus legends. They involve the medieval preoccupation with sin, especially sexual sins of women. Victims may have been experiencing waking dreams or sleep paralysis. Also, nocturnal arousal, orgasm or nocturnal emission could be explained by the idea of creatures causing an otherwise guilt-producing and self-conscious behavior.
Purported victims of incubi could have been the victims of sexual assault by a real person. Rapists may have attributed the rapes of sleeping women to demons in order to escape punishment. A friend or relative may have assaulted the victim in her sleep. The victims and, in some cases the clergy, may have found it easier to explain the attack as supernatural rather than confront the idea that the attack came from someone in a position of trust.
Ancient and religious descriptions
One of the earliest mentions of an incubus comes from Mesopotamia on the Sumerian kings' list, ca. 2400, where the hero Gilgamesh's father is listed as Lilu (Lila). It is said that Lilu disturbs and seduces women in their sleep, while Lilitu, a female demon, appears to men in their erotic dreams. Two other corresponding demons appear as well: Ardat lili, who visits men by night and begets ghostly children from them, and Irdu lili, who is known as a male counterpart to Ardat lili and visits women by night and begets from them. These demons were originally storm demons, but they eventually became regarded as night demons due to mistaken etymology. Incubi and succubi were said by some not to be different sexes, but the same demons able to change their sex. A succubus would be able to sleep with a man and collect his sperm, and then transform into an incubus and use that seed on women. Their offspring were thought to be supernatural in many cases, even if the actual genetic material originally came from humans. Though many tales claim that the incubus is bisexual, others indicate that it is strictly heterosexual and finds attacking a male victim either unpleasant or detrimental.
There are also numerous stories involving the attempted exorcism of incubi or succubi who have taken refuge in, respectively, the bodies of men or women. Incubi are sometimes said to be able to conceive children. The half-human offspring of such a union is sometimes referred to as a cambion. The most famous legend of such a case includes that of Merlin, the famous wizard from Arthurian legend. According to the Malleus Maleficarum, exorcism is one of the five ways to overcome the attacks of Incubi, the others being Sacramental Confession, the Sign of the Cross (or recital of the Angelic Salutation), moving the afflicted to another location, and by excommunication of the attacking entity, "which is perhaps the same as exorcism."
On the other hand, the Franciscan friar Ludovico Maria Sinistrari stated that incubi "do not obey exorcists, have no dread of exorcisms, show no reverence for holy things, at the approach of which they are not in the least overawed."
(Senex is Latin for old man. In Ancient Rome, the title of Senex was only awarded to elderly men with families who had good standing in their village. In Jungian analytical psychology, examples of the senex archetype in a positive form include the wise old man or wizard. The senex may also appear in a negative form as a devouring father or a doddering fool.)