In human affairs there is no effect without its adequate cause. Codified law, custom and ethics, the three determiners and regulators of human conduct, have all their reasons. If there is a double standard of sex-morality there must be a reason for it. What is this reason? Is this reason still extant? Is there still any justification for the existence of the double moral standard? Have not any other reasons arisen for a change of this double standard? In modern times law and ethics do not know of any double standard of sex-morality. In no civilized country do the laws punish any voluntary sexual misconduct but adultery, and in the latter the prohibition is for men and women alike. Ethics, on the other hand, allows sexual relations in marriage only, and then mostly for the purpose of propagation. Even such a radical as Zola says: “Si l’enfant n’est pas au bout, l’amour n’est qu’une saleté inutile.” But as far as custom is concerned there is no question of the existence of a double standard of sex-morality. Even the most violent, rabid free-lover will resent any allegations of a dissolute character in his mother, while he will listen with perfect equanimity to narrations of the fast life of his father. Whence comes this difference, which seems to be ingrained in the heart of every man and woman? What is the cause of this phenomenon? The answer that men with the power in their hands have sexually enslaved womankind, shows not only ignorance of history and biology (no species could survive for any length of time without the harmonious coöperation of the two sexes. Where the female of the species is actually kept subject to the male, where she is treated with cruelty by him, or where the male neglects to protect and take loving care of the female, the species has no survival power and dies), but also poor logic. If the double standard of morality were not due to racial evolution, if it could have been changed without hurting the race, sensual men would have changed it long ago, because it is against these men’s interest to have all women live in strict chastity. An unchaste man needs an unchaste female partner. If all women—prostitutes included, sic!—were chaste, where on earth could he get his partner? Hence the assertion, frequently found, especially in feministic literature, that men-made laws sexually enslaved women, is entirely illogical.