It will thus be seen how the idea and the practice of chastity have grown up from a physiological basis, and may be inseparably interwoven with the essential structure of our physical organization. Chastity is the government of the sexual instinct by the higher reason or wisdom--_i.e._, by our perception of the providential law which governs our human nature. Customs, and the laws concerning marriage and the relations of the sexes which represent them, are checks or guides imposed upon the blind sexual impulse by the enlightened common-sense of mankind. These customs and laws, acting slowly but persistently upon society, generation after generation, modify the habits of thought in the adult, and the methods of education in the child. It is thus that the idea of chastity arises, and its practice becomes possible and easy. It springs as a physiological habit from the effects for good and evil which are produced by the modifications of our nervous system through education and custom. The universal experience of the world has proved that directly human beings join in societies, they are compelled to impose guides upon the exercise of the sexual powers, in the interest of society itself. This check upon the blind, unrestrained use of the sexual impulse is a necessity imposed by our physiological structure for the well-being and continuance of the race. The most important practical results flow from obedience to the physiological law of chastity thus imposed upon our sexual nature. The necessary mutual aid and respect of the sexes, procreative vigour and the production of a fine race, and the extirpation of the loathsome disease caused by promiscuous intercourse, are all subject to the guidance of chastity. The tremendous power of creative law, which is quite beyond our reach, demands that the blind instinct of sex be governed and enlightened by this inevitable higher control, and that human law be moulded upon Divine law. The mighty and transforming physiological power of habit, with its tendencies transmitted by both men and women to their offspring, shows the method by which the law of chastity must gradually extend its sway over the human race. The choice between inevitable degeneracy and sure improvement is left to our relatively free will, but the law which governs results is beyond our reach. Race after race has perished from blind or wilful ignorance, or neglect of the inexorable moral law bound up with our physiological structure. The importance of the truths now insisted on can be more fully realized in their wide bearings by experienced and religious physicians than by any other class in the community. If they will learn to trust to the sacredness of the maternal instinct, and instruct mothers, as well as fathers, in these vital truths concerning our sexual structures, they will exercise a mighty influence in the elevation of our race.