Rabbinic material isn’t always dull reading; in fact, more often than not, it contains some very fascinating and entertaining cases about life in the medieval era. Jewish folklore continues to enchant many Hassidic and Sephardic Jews, many of whom, still believe in the stories about demons in rabbinical tradition. Keep in mind that Maimonides wrote his Mishnah Torah and “Guide for the Perplexed” to help wean the Jews of his time away from believing in such superstitions. Such a position did not make Maimonides very popular among the mystics of the Kabbalah.
R. Joshua Tractenburg writes in his “Jewish Magic and Superstition: A Study in Folk Religion”:
“Was a man or woman who had been seduced by a demon to be regarded as an adulterer? And if so, was such a woman to be “forbidden” to her husband? If, today, the issue strikes us as grotesque it is only because we have lost faith in the realities of the medieval world. Isaac b. Moses of Vienna, in the thirteenth century, considered this question at length and solemnly concluded that a person who had been seduced by a spirit was not to be held guilty of fornication.
In substantiation of his decision he recalled a legend of a pious man who was sorely grieved because a demon in human shape had enticed him into an indiscretion. The prophet Elijah appeared to him and consoled him: since this was a demon he had committed no offense. “If he had been guilty,” R. Isaac deduced, “Elijah would not have come to him, nor spoken with him, nor would he have acquitted him.”
Three centuries later a Polish rabbi was consulted in the case of a married woman who had had relations with a demon which appeared to her once in the shape of her husband, and again in the uniform of the local petty count.
Was she to be considered an adulteress? this rabbi was asked, and was she therefore to be “forbidden” to her husband, since she might have had intercourse with this demon of her free will? The judge absolved her of all guilt and “permitted” her to her husband” (Or Zarua, I, §124, p. 22c;—Responsa of R. Meir b. Gedaliah (Maharam) of Lublin).
I suspect that Maimonides and Sherlock Holmes probably would have offered a much simpler explanation, as would Sigmund Freud for such cases.