A heightened self-consciousness and an antagonism to authority so often follow the attainment of puberty that they are usually considered to be its results. My own experience with boys satisfies me that this conclusion is not correct. Self-consciousness, when it occurs in boyhood, is usually the result of an unclean inner life. Puberty merely increases the self-consciousness by intensifying its cause. When the mind is clean there is no marked change in this respect at puberty. The antagonism to authority so often observed after puberty is the product of unsatisfactory external influences. With puberty the desire to stand well with others, and in particular the desire to seem manly, increases. If a debased public opinion demands of a boy the cheap manliness of profanity, tobacco, and irreverence, the demand creates a plentiful supply, while it also suppresses as priggish or "pi" any avowed or suspected devotion to higher ideals. A healthy public opinion, working in harmony with a boy's nobler instincts, calls forth in him an earnest devotion to high ideals, and causes him to exercise, on the development of his powers and in a crusade against wrong, the new energies which a wholesome puberty places at his disposal. CHAPTER I. PREVALENCE OF IMPURITY AMONG BOYS: THE AUTHOR'S OWN EXPERIENCE. Of the perils which beset the growing boy all are recognised, and, in a measure, guarded against except the most inevitable and most fatal peril of all. In all that concerns the use and abuse of the reproductive organs the great majority of boys have hitherto been left without adult guidance, and have imbibed their ideas from the coarser of their companions and from casual references to the subject in the Bible and other books. Under these conditions very few boys escape two of the worst dangers into which it is possible for a lad to fall--the artificial stimulation of the reproductive organs and the acquisition of degraded ideas on the subject of sex. That many lives are thus prematurely shortened, that many constitutions are permanently enfeebled, that very many lads who might otherwise have striven successfully against the sexual temptations of adult life succumb--almost without a struggle--to them, can be doubted by no one who is familiar with the inner life of boys and men.