The ascetics of early Christianity first denied sexuality--for example, by self-castration, or by flight into solitude--in order subsequently to affirm it the more strongly. Our modern _fin-de-siècle_ ascetics, above all, the three most successful literary apostles of asceticism--Schopenhauer, Tolstoi, and Weininger--at first affirmed their sexuality most intensely, in order subsequently to deny it in the most fundamental manner. They studied voluptuousness, not merely in the ideal, but also in reality. For this reason, also, they have furnished us with more valuable conclusions regarding its nature and its significance in the life of individual men than we can obtain from the visions of the early Christian ascetics. This is true above all of Schopenhauer and Tolstoi. Schopenhauer had first to endure in his own person the whole tragedy of voluptuousness, to experience the elemental force of the sexual impulse, the “enmity” of love (see his own account given to Challemel-Lacour), before he proceeded to grasp the full significance of the ascetic idea. His asceticism is intimately associated with his sensuality, and with the consequences of its activity. I believe that I have myself recently furnished a striking proof of this fact by the publication of a hitherto unknown holograph manuscript of the philosopher,[58] by which it is clearly established that he had suffered from syphilitic infection. In this connexion we find the explanation of the close relationship which Schopenhauer himself postulated between the “wonderful venereal disease” and asceticism. From his own utterances regarding syphilis, and, above all, from the fact that he himself had suffered from the disease, we are able to grasp the significance that syphilis had in the conception of his ascetic views, which were developed under the immediate influence of his experiences, sorrows, and passions; whereas in old age, when the elemental force of the sexual impulse, and the unhappy consequence of yielding to it, no longer troubled him, there appeared in his thought a distinctly happier colouring.