[231] Pausanias, _Achaia_, Chapter XVII. The ancient Babylonians believed in a certain "maid of the night," who appeared to men in sleep and roused without satisfying their passions. (Jastrow, _Religion of Babylonia_, p. 262.) This succubus was the Assyrian Liler, connected with the Hebrew Lilith. There was a corresponding incubus, "the little night man," who had nocturnal intercourse with women. (Cf. Ploss, _Das Weib_, 7th ed., pp. 521 et seq.) The succubus and the incubus (the latter being more common) were adopted by Christendom; St. Augustine (_De Civitate Dei_, Bk. XV, Ch. XXIII) said that the wicked assaults of sylvans and fauns, otherwise called incubi, on women, are so generally affirmed that it would be impudent to deny them. Incubi flourished in mediæval belief, and can scarcely, indeed, be said to be extinct even to-day. They have been studied by many authors; see, e.g., Dufour, _Histoire de la Prostitution_, vol. v, Ch. XXV, Saint-André, physician-in-ordinary to the French King, pointed out in 1725 that the incubus was a dream. It may be added that the belief in the succubus and incubus appears to be widespread. Thus, the West African Yorubas (according to A.B. Ellis) believe that erotic dreams are due to the god Elegbra, who, either as a male or a female, consorts with men and women in sleep. [232] "If any man's seed of copulation go out from him, then he shall bathe all his flesh in water and be unclean until the even. And every garment, and every skin, whereon is the seed of copulation, shall be washed with water and be unclean until the even." Leviticus, XV, v. 16-17. [233] It should be added that the term _pollutio_ also covers voluntary effusion of semen outside copulation. (Debreyne, _Moechialogie_, p. 8; for a full discussion of the opinions of theologians concerning nocturnal and diurnal pollutions, see the same author's _Essai sur la Théologie Morale_, pp. 100-149.) [234] _Memoirs_, translated by Bendyshe, p. 182. [235] _Sexual Impotence_, p. 137. [236] _L'Hygiène Sexuelle_, p. 169. [237] _Sexualleben und Nervenleiden_, p. 164. [238] I may here refer to the curious opinion expressed by Dr. Elizabeth Blackwell, that, while the sexual impulse in man is usually relieved by seminal emissions during sleep, in women it is relieved by the occurrence of menstruation. This latter statement is flagrantly at variance with the facts; but it may perhaps be quoted in support of the view expressed above as to the comparative rarity of sexual excitement during sleep in young girls. [239] Löwenfeld has recently expressed the same opinion. Rohleder believes that pollutions are physically impossible in a _real_ virgin, but that opinion is too extreme.