All these deep-seated differences, the whole great fact of sexuality with its infinite bearings on the social, the physical, and the moral life of man, look to the accomplishment of one purpose, to the performance of one function. That purpose, that function, is the reproduction of the species, the transmission of life. Around this central, mysterious power are grouped all other faculties and aspirations. It is the strongest of all instincts, the most uncontrollable of all passions the most imperious of all demands. Nature everywhere points to it as the most sacred object of the individual's physical existence. The botanist can tell of plants rooted in such exposed and barren soils that no nourishment is afforded for leaves or fronds; but the flower and the seeds mature; the zoologist has strange stories to relate of the males of lower forms of animal life, who, when they have once completed the act of reproduction, straightway wither and die, as if this alone was the purpose of their creation.

The instinct of self-preservation itself in unnumbered instances has disappeared before the tyrannical demands of sexual love. There is an impulse in organic beings which they feel to be of greater moment than all else, weighed against which life itself is a feather in the balance, the scope of which is not bounded by the confines of the individual, but stretches into eternity and to the limits of all things. This impulse is the perpetuation of their kind - once more the transmission of life. It is something apart from all else in nature. Contemplating it with the inspired eye of genius, Bichat, the profoundest of modern physiologists, speaks of it as a phenomenon which science must study by itself, unconnected with the other functions of the individual. Regarding it with the practical observation of a man of the world, an eminent New York surgeon writes : " The strongest motive of human action, the most powerful mainspring within us all, is the sexual desire, with the domestic relations which rest upon it. It is stronger in its influence, controls more men, causes the commission of more crimes and more good deeds, than any other impulse." How vitally important is it, therefore, how intimately does it concern the weal of our nation, to understand its nature and its laws, its government, its dangers, its regulation ! In what direction can we with greater propriety extend the domain of hygiene ?