The policy of maintaining mystery and secrecy concerning sex has failed with adults even more sadly than with children. Health and morals have suffered incalculable injury. The sexual evils of our time are not as bad as were those of the ancient civilizations, but we have little reason to be proud of the slight progress made. But why should we expect the human to make progress when sexual problems have been kept in darkness? The wonder is that, with the prevailing dark outlook on sexual life throughout the past nineteen centuries, the world has not developed more sexual vice. Innate animalistic appetites have tended to lead downward, and surely the policy of silence has offered no counteracting influence towards higher living. While religion and ethics, by means of certain rules of conduct, have maintained certain sexual standards, they have not kept vast numbers of humans from falling far below those standards into utter degradation. The modern teachers of religion and ethics have prevented general sexual degradation, but they have failed to give human sexuality any decided uplift. The reason for this failure is the policy of mystery and silence. The teachers of religion and ethics have preferred to let general and more or less abstruse rules govern conduct in sexual lines. Until recent years there have been few sermons in which common sexual problems have been presented so that the preacher's meaning has been clear to all. On the contrary, there has been universal mystery and evasion concerning the greatest facts of life. [Sidenote: Sexual instincts offer no guidance.] Many people have justified the mystery thrown around sexual processes on the theory that the reproductive instincts of mature people are sufficient guides for conduct. This involves a misunderstanding of sexual instincts of the higher mammals which are often unscientifically cited as models for human imitation. In these animals sexual union is instinctively determined, because normally the sexual hunger or excitement of both sexes is stimulated and controlled by the physiological condition of the female at the times favorable for fertilization (_i.e._, at the oestrual periods). For example, a pair of dogs living in close companionship show signs of mutual sexual desires only for a few days at the semi-annual oestrual or fertile periods of the female. It occasionally happens that the males of various wild and domesticated mammals exhibit signs of automatic sexual excitement (_i.e._, not caused by the stimulus arising from the physiological condition of the female); but in such cases of male excitement outside of the mating or oestrual periods, the normal females invariably offer instinctive opposition to attempted union by abnormally or automatically excited males. Thus, directly and indirectly, there is instinctive control and limitation of sexual union among the animals that are most closely related to the human race.