Let us now consider the opinion of Dr. Clement Dukes, the medical officer of Rugby School and the greatest English authority on school hygiene. In the preface to the fourth edition of his well-known work _Health at School_, Dr. Dukes writes: "I have studied children in all their phases and stages for many years--two years at the Hospital for Sick Children in 61 Ormond Street, London, followed by thirty-three years at Rugby School--a professional history which has provided me with an almost unique experience in all that relates to the Health and Disease of Childhood and Youth, and has compelled constant and steady thought upon every aspect of this problem." In an earlier work, _The Preservation of Health_, Dr. Dukes gives his estimate of the prevalence of masturbation, and quotes the opinion of other authorities whose credentials he has verified; In this work, on page 150, he writes of masturbation: "I believe that the reason why it is so widespread an evil--amounting, I gather, although from the nature of the case no complete evidence can ever be accurately obtained, to somewhere _about 90 to 95 per cent. of all boys at boarding-schools_--is because the boy leaves his home in the first instance without one word of warning from his parents ... and thus falls into evil ways from his innocence and ignorance alone.... This immorality is estimated by some at 80 per cent., by others at 90 per cent. Another says that not 10 per cent. are innocent. Another that it has always begun at from eight to twelve years of age. Others that it is always worst amongst the elder boys. Others that 'it is universal.'" Professor Stanley Hall, in his great work on _Adolescence_, after a similar and exhaustive review of the numerous works on this subject in different languages, concludes: "The whole literature on the subject attests that whenever careful researches have been undertaken the results are appalling as to prevalence." And yet there are people who deprecate purity-teaching for boys because they feel that a boy's natural modesty is quite a sufficient protection, and that there is danger of destroying a boy's innocence by putting ideas into his head! To hear such people talk, and to listen to the way in which they speak of self-abuse as though it implied monstrous moral perversion, one would think that the condition of morals when they were young was wholly different. The great novelist Thackeray gives little countenance to this opinion when he writes in _Pendennis_: "And, by the way, ye tender mothers and sober fathers of Christian families, a prodigious thing that theory of life is as orally learned at a great public school. Why if you could hear those boys of fourteen who blush before mothers and sneak off in silence in the presence of their daughters, talking among each other--it would be the woman's turn to blush then. Before he was twelve years old little Pen had heard talk enough to make him quite