Very early in the development of species it was ascertained by nature’s slow but sure experiments that the establishment of two sexes in separate organisms, and their differentiation, was to the advantage of the species. Therefore, out of the mere protoplasmic masses, the floating cells, the amorphous early forms of life, grew into use the distinction of the sexes,—the gradual development of masculine and feminine organs and functions in two distinct organisms. Developed and increased by use, the distinction of sex increased in the evolution of species. As the distinction increased, the attraction increased, until we have in all the higher races two markedly different sexes, strongly drawn together by the attraction of sex, and fulfilling their use in the reproduction of species. These are the natural features of sex-distinction and sex-union, and they are found in the human species as in others. The unnatural feature by which our race holds an unenviable distinction consists mainly in this,—a morbid excess in the exercise of this function. It is this excess, whether in marriage or out, which makes the health and happiness of humanity in this relation so precarious. It is this excess, always easily seen, which law and religion have mainly striven to check. Excessive sex-indulgence is the distinctive feature of humanity in this relation. To define “excess” in this connection is not difficult. All natural functions that require our conscious co-operation for their fulfilment are urged upon our notice by an imperative desire. We do not have to desire to breathe or to digest or to circulate the blood, because that is done without our volition; but we do have to desire to eat and drink, because the stomach cannot obtain its supplies without in some way spurring the whole organism to secure them. So hunger is given us as an essential factor in our process of nutrition. In the same manner sex-attraction is an essential factor in the fulfilment of our processes of reproduction. In a normal condition the amount of hunger we feel is exactly proportioned to the amount of food we need. It tells us when to eat and when to stop. In some diseased conditions “an unnatural appetite” sets in; and we are impelled to eat far beyond the capacity of the stomach to digest, of the body to assimilate. This is an excessive hunger. We, as a race, manifest an excessive sex-attraction, followed by its excessive indulgence, and the inevitable evil consequence. It urges us to a degree of indulgence which bears no relation to the original needs of the organism, and which is even so absurdly exaggerated as to react unfavorably on the incidental gratification involved; an excess which tends to pervert and exhaust desire as well as to injure reproduction.