性行为的类型

人們毫無例外地都知道人在睡眠時有體驗性反應的能力。可是，在特定的文化和歷史時期，人們只認為男人才有這種能力。例如，《聖經》告訴我們在古希伯萊書裏，一個在睡眠中有性高潮的男人必須去為淨化而施洗禮。他無意中的射精被稱為“污點”，使他變得“不乾淨了”[《利未記》（聖經《舊約全書》中的一卷）第15章；申命記（舊約全書中的一卷）第23章]。而女人沒有與男人可比的條件。因為她們不會射出任何東西，人們並不關注她們的自發性高潮。

可是，在中世紀，隨著人們再一次相信古代人所篤信的夜魔的存在，這種局面略有所改變。那時，人們把性夢歸於魔鬼的出現，既有躺在男人身下的女魔鬼（被稱為女妖），也有臥在女人身上的男魔鬼（被稱為惡魔）。這種猜想後來於15-17世紀在“尋找”和迫害“女巫”中起到了重要的作用，這是一連串令人壓抑的群體歇斯底里和人類荒唐的歷史事件之一。

惡魔（中世紀書籍插圖） Incubus Medieval book illustration

It has always been well known that human beings are capable of experiencing sexual responses while they are asleep. In certain cultures and historical periods, however, people ascribed this capacity only to males. For example, the Bible tells us that, among the ancient Hebrews, a man who had an orgasm in his sleep was required to take a ritual bath for purification. His involuntary ejaculation of semen was called a "pollution" which made him "unclean" (Leviticus 15; Deuteronomy 23). There was no comparable requirement for women. Since women do not ejaculate anything, nobody paid any attention to their spontaneous orgasms.
However, this changed somewhat in the Middle Ages with a revival of ancient beliefs in nightly demons. Sexual dreams could now be ascribed to visits by the devil who appeared either in the form of a woman, lying under a man (a so-called succubus) or as a man, lying on a woman (an incubus). This idea later played an important role in the “discovery” and persecution of “witches” in the 15th - 17th centuries, one of the most depressing episodes of mass hysteria and human folly.