[Sidenote: Relative passion of men and women.] There is the widespread misunderstanding among young men that sexual hunger is as insistent in virtuous young women as in themselves and that therefore illicit gratification is a mutual gain and responsibility. Some young men may be guided by the information that there is much reliable evidence indicating that, while an innate tendency towards general emotions of affection is strong in the average young woman, there is general absence of the localized passions that naturally and automatically develop in young men. In other words, the first definite sexual temptation is likely to come to a young woman from outside herself, and young men should be impressed with their responsibility for allowing even the beginning of situations that may arouse dormant but dangerous instincts. Sec. 10. _The Fifth Problem for Sex-education: Sexual Morality_ In this lecture I shall set forth the proposition that a definitely organized scheme of education should aim directly at making young people strict adherents of the established code of sexual morality. For brevity, I shall occasionally speak of morality and immorality, omitting the qualifying word "sexual." [Sidenote: Definition of sexual morality.] This lecture, in fact this entire series of lectures on sex-education, is based on the fundamental proposition that sexual morality demands that sexual union be restricted to monogamic marriage, and conversely, that such sexual relation outside of marriage is immoral. Such a definition of sexual morality is accepted by church and state and the chief citizens in every civilized country. It is the only practical definition which is satisfactory to the vast majority of educated American men and women, even to those who believe in freedom of divorce and in forgiveness for youthful transgressions of the accepted moral code. Sexual morality has had changeable standards, and in other times and countries custom has made polygamy and promiscuity acceptable as moral; but the monogamic ideal of morality now prevails in the world's best life. [Sidenote: Morality in America and Europe.]