Foul thoughts, once they enter the mind, corrode it. The sensual glance, the bawdy laugh, the ribald jest, the smutty story, the obscene song may be met with on street corner, in the car, train, hotel lobby, lecture hall and workshop. Mental unchastity ends in physical unchastity. The habit common to most adolescent boys and young men of relating smutty stories, repeating foul jokes and making indecent allusions destroys respect for virtue. In addition there are such direct physical causes of undue adolescent sexual excitement as constipation and alcoholism, and such mental ones as nervous irritability. To the constant discussion and speculation regarding sex and its mysteries by the adolescent young male, must be added the artificial idea that idle prattling on the subject is a sign of "manhood." Thus many young men whose natural trend is in the direction of decency and right sexual living, "step out" or "go to see the girls," as the phrase is, because they think that otherwise "they are not real men." More subtle in its evil effect, yet somewhat less dangerous physically, perhaps, than the professional prostitute is the lure of the "hidden" prostitute, who carefully conceals her derelictions, and publicly wraps herself in a mantle of virtue. PROSTITUTION The training of the average male mind in impure language and thought during boyhood and adolescence, the cultivation of his animal at the expense of the moral nature, often leads the adolescent to seek satisfaction by frequenting the prostitute. _Prostitution_, known as the "social evil," is promiscuous unchastity for gain. It has existed in all civilized countries from earliest times. Prostitution abuses the instinct for reproduction, the basic element of sex, to offer certain women a livelihood which they prefer to other means. Love of excitement, inherited criminal propensities, indolence and abnormal sex appetite are first causes of prostitution. Difficulty in finding work, laborious and ill-paid work, harsh treatment of girls at home, indecent living among the poor, contact with demoralizing companions, loose literature and amusements are secondary causes. They all contribute to debauch male and female youth and lead it to form dangerous habits of vicious sensual indulgence. Prostitution seems inseparable from human society in large communities. The fact is acknowledged in the name given it, "the necessary evil." Regulation and medical control only arrest in a degree the spread of venereal diseases to which prostitution gives rise. The elementary laws on which prostitution rests seems to be stronger than the artificial codes imposed by moral teaching. It is an evil which must be combatted _individually_. Men are principally responsible, in one way or another, for the existence of the social evil. In the case of the young man, abstention is the only cure for the probable results of indulging his animal passions by recourse to the prostitute.