Finally, the educational application of the fourth aim demands some explanation. Sometime in the adolescent period all young people should learn the essential facts regarding the two social diseases and their relation to immoral living. There is the widespread impression that those advocating sex-education believe in giving great prominence to the social diseases; but in opposition to this I cite the report of a committee of the American Federation for Sex Hygiene, published in the _Journal of the Society of Sanitary and Moral Prophylaxis_, January, 1913, and later reprinted as a pamphlet by the American Social Hygiene Association. In that report there are _twenty-three_ recommendations concerning sex-instruction; but _only_ one mentions social diseases and in these words: "During the later period of adolescence ... there should be given ... special instruction as to the character and dangers of the venereal diseases." That seems sufficient. It is not desirable that young people should review the horrible facts relating to perverted sexuality. Ten or twenty brief and authoritative statements quoted impressively from medical and social literature ought to give fair warning of lurking dangers in immoral living. More extensive information has often proved dangerous. I would gladly advocate that this dark side of life be kept in sealed books if I did not know that so many young people need forewarning and definite guidance. Our educational system will not do its full duty if it fails to offer the needed help so that it may be obtained by all adolescent young people who are not so fortunate as to be guided by parents and other personal teachers. FOOTNOTES: [12] To avoid misunderstanding, let me repeat from the first lecture that I am constantly thinking of sex-education in the larger sense; and instruction in schools can be, at best, only a part. IV THE TEACHER OF SEX-KNOWLEDGE Sec. 18. _Who Should Give Sex-instruction?_ A large number of people have been convinced that young people need knowledge which will help them face the great problems of sex; but they withhold their approval of the sex-education movement because they are not satisfied that proper teachers exist. It is, therefore, evident that we cannot make permanent progress by emphasizing the need of sex-education unless we can give assurance that qualified teachers are available. [Sidenote: The teacher most important.]