In consequence of the diffusion of Christianity, woman became man’s companion and equal, and her life, the sexual life included, acquired a deeper significance, owing to the stress which that religion laid on chastity as a virtue, and as a result of the educational influence of woman in the family circle. With the progress of civilization the sexual life of woman comes to exhibit its activities only within the bounds of morality and law, which in human society have replaced the crude rule of nature, and have supplied regulations adapted to the changing phases of sexual vital manifestations. The wise adaptation of these regulations requires, however, a full understanding of the mental and physical processes, an exact recognition of the bodily states and intellectual sensibilities, of woman regarded as a sexual being. Modern culture and the social organization of the present day, in association with the resulting sexual neuropathy of women, have exercised on their sexual life an influence as powerful as it is unfavorable, manifesting itself in the overpowering frequency of the diseases of women. In one of the most thoughtful books ever written on the subject of woman, _Michelet’s L’Amour_,[13] the author remarks that every century is characterized by the prevalence of certain diseases: thus, in the thirteenth century, leprosy was the dominant disease; the fourteenth century was devastated by bubonic plague, then known as the black death; the sixteenth century witnessed the appearance of syphilis; finally, as regards the nineteenth century, “_se siècle sera nommé celui des maladies de la matrice_”.[14] It is certain that the education and mode of life of the modern woman belonging to the so-called upper classes are, as far as sexual matters are concerned, in direct opposition to those that are agreeable to nature and those that the laws of health demand.