Most men are sorely tempted to lack of self-control, and to the misuse of their sexual endowment in a variety of ways: and the maintenance of chastity--never an easy ideal--is made doubly difficult by the fact that in the existing social system marriage, except among the poorer classes, is commonly deferred until an age much later than that at which a man becomes physically mature, and also by the widespread prevalence, in masculine society, of a corrupt public opinion which regards sexual indulgence as morally tolerable, or even as essential to physical health. This latter doctrine, even were it as true as it is in fact false, would not in any case justify a man in taking advantage of a woman's ruin: but experience shows that there is no form of sin or indulgence which so effectually degrades a man's moral outlook, blunts his finer perceptions, and destroys the instinct of chivalry within him, as does the sin of fornication. The majority of those who practise promiscuous sexual intercourse are found to greet with frank and obviously genuine incredulity the assertion that there exists a not inconsiderable proportion of men whose lives are clean; while at the other end of the scale men of pure lives and clean ideals often find it difficult to believe that more than a small minority of peculiarly degraded individuals are clients of the women of the streets. The publication of the Report of the Royal Commission on Venereal Diseases, taken in conjunction with what is known or suspected with regard to the state of morals in the Army, has had the effect of drawing public attention to certain aspects of these problems. The Victorian convention of prudery has to a great extent been discarded. The subject is freely discussed, and it is generally acknowledged that something must be done. There is danger, however, lest public opinion, rightly concerned to promote measures for the eradication of disease, should ignore the essentially moral aspect of the matter. A Christian man is here concerned, not simply with the personal struggle against the temptations of sex in his own life, but with a further conflict on behalf of Christian ideals against the public opinion of the world.