[Sidenote: The many-sided bearings of sex.] In this first lecture I want to make it clear that the role of sex in human life is vastly greater than that directly involved in sexual activity. I shall in several lectures touch the big problems from the standpoint of the sexual instincts as these play an important part in social, psychical, and aesthetic life even if they are rarely exercised, physiologically, or if, as in millions of individuals, they never come to mean more than possibilities of sexual activity for which opportunities in marriage do not come. I am especially anxious to avoid the narrow viewpoint of numerous writers on sex-hygiene who seem to overlook the fact that sexual functioning is only a prominent incident in the cycle of sexual influences in the lives of most people. Human life, and especially marriage, should no longer be regarded from the mere biological point of view as for the sole purpose of reproductive activity. It is a far more uplifting view that the conscious or unconscious existence of the sexual instincts, with or without occasional activity, affords the fundamental physical basis for states of mind that may profoundly affect the whole course of life in every normal man and woman. Supplementary to this section on the "Misunderstanding of Sex," I suggest the reading of Chapters I-VI of "Sex" by Geddes and Thomson, the "Problems of Sex" by the same authors, and Chapter VI in "The Wonder of Life" by Thomson. Sec. 3. _The Need of Sex-Instruction_ [Sidenote: The old silence and the new enlightenment.] The time-honored policy has been one of silence and mystery concerning all things sexual. Everything in that line has long been considered impure and degraded and, therefore, the less said and the less known, the better, especially for young people. Such has been the almost universal attitude of parents until within the present century, when many have awakened to the fact that the policy of silence has been a gigantic failure, because it has not preserved purity and innocence and because it has allowed grave evils, both hygienic and moral, to develop under the cloak of secrecy. [Sidenote: Children will not remain ignorant.]