In these Essays I have tried to set forth, as clearly as I can, certain fundamental principles, together with their practical application to the life of our time. Some of these principles were stated, more briefly and technically, in my larger Studies of sex; others were therein implied but only to be read between the lines. Here I have expressed them in simple language and with some detail. It is my hope that in this way they may more surely come into the hands of young people, youths and girls at the period of adolescence, who have been present to my thoughts in all the studies I have written of sex because I was myself of that age when I first vaguely planned them. I would prefer to leave to their judgment the question as to whether this book is suitable to be placed in the hands of older people. It might only give them pain. It is in youth that the questions of mature age can alone be settled, if they ever are to be settled, and unless we begin to think about adult problems when we are young all our thinking is likely to be in vain. There are but few people who are able when youth is over either on the one hand to re-mould themselves nearer to those facts of Nature and of Society they failed to perceive, or had not the courage to accept, when they were young, or, on the other hand, to mould the facts of the exterior world nearer to those of their own true interior world. One hesitates to bring home to them too keenly what they have missed in life. Yet, let us remember, even for those who have missed most, there always remains the fortifying and consoling thought that they may at least help to make the world better for those who come after them, and the possibilities of human adjustment easier for others than it has been for themselves. They must still remain true to their own traditions. We could not wish it to be otherwise. The art of making love and the art of being virtuous; two aspects of the great art of living that are, rightly regarded, harmonious and not at variance remain, indeed, when we cease to misunderstand them, essentially the same in all ages and among all peoples. Yet, always and everywhere, little modifications become necessary, little, yet, like so many little things, immense in their significance and results. In this way, if we are really alive, we flexibly adjust ourselves to the world in which we find ourselves, and in so doing simultaneously adjust to ourselves that ever-changing world, ever-changing, though its changes are within such narrow limits that it yet remains substantially the same. It is with such modification that we are concerned in these Essays.