So far in writing of marriage and of the irregular partnerships entered into outside of marriage I have ignored the question of venereal diseases and of prostitution, so intimately connected with them, but to continue to do this would be to make my inquiry useless, as, properly speaking, they constitute the central problem of the sexual relationships. There are no other factors of the same importance to motherhood and to the life and health of the race. Without doubt the subject is eminently complicated, while the problems involved are so immense, far-reaching and perilous, linking themselves with the deepest interests of the race, that I hesitate almost in making an attempt to discuss so wide a subject briefly, and necessarily inadequately, in the short space at my disposal. Yet it is clearly impossible to take the easy way and pass these matters over in silence. On the question of prostitution I have written already in my earlier book, _The Truth about Woman_, where I stated as truthfully as I could some facts I had come to know about the prostitute class, as well as my own opinions on this very complex social phenomenon. I shall, therefore, now as far as possible leave this side of the problem without further comment. It must, however, be remembered that the problem of prostitution and the problem of venereal diseases are inseparably interconnected, the former evil being the chief cause of the latter. Indeed, if prostitution could be ended venereal diseases would of themselves disappear. And here we touch at once the grave difficulty of the position. These diseases are set apart from all other sicknesses of our bodies. Moral considerations become confused with practical values. I do not see that this in itself can be wrong. For there can be no greater ideal than that of removing the poisonous sting that with such abundant activity has worked evil in our midst. There is, however, danger in too much and wrongly directed moral enthusiasm. It is of vital importance that a contagious disease should be isolated and cured, and if moral condemnation acts to defeat these objects, it cannot but be a danger. A contagious disease that must be kept secret cannot be properly dealt with and healed. I hope I made my own position clear when I wrote on prostitution, where I tried to avoid a purely moral and idealistic treatment of the subject.[99] I shall follow the same plan here. I shall limit myself to the aspects of the question that to me seem to be of special importance, choosing by preference facts about which I have some little personal knowledge, or a fixed opinion of my own. In this way I may be able to contribute a word or two of worth to this difficult question.