"In the fourth grade of a certain elementary school of a Western city there are three backward boys who have been in this grade for two years, though they are bright enough in the things of the street. They are in a more or less hostile attitude towards all that goes on in the schoolroom, probably because they cannot succeed in it themselves, and so they would like to escape from it or destroy it. Now, they make it unpleasant, so far as they are able, for all the boys in the grade who apply themselves to their tasks and get 'good marks.' On the playground these dullards 'pick on' the 'bright' boys; and in the school they ridicule them by 'snickering' at them, or 'making faces' at them, and so on, with the result that they deter some boys from doing their best in the schoolroom. These same three ill-adjusted boys will make fun of their mates who come to school 'dressed up in fine togs.' They are themselves attired in plain clothes suited to the rough experience of the street, and they resent the adoption of different styles by any of their associates. Further, they show jealous feeling towards boys who come from 'better' homes than their own, or from more 'aristocratic' parts of the city.... "It will not be necessary here to do more than to mention the chief incitement to jealousy after the beginning of the adolescent upheaval, and lasting well on into middle life. The testimony of autobiographers, as well as the observations of psychologists, indicates that rivalry for sex favours gives rise to most of the jealous attitudes of the adolescent up until full maturity is reached. Often, no doubt, it is the main cause of the jealousies of some people throughout their lives; but, normally, other and more general interests become stronger and more vital as maturity is approached. But, from the age of fifteen or sixteen on to twenty-five, or beyond, the sex needs and interests are supreme, and the individual is sensitive to sex relations above all others. No pain is so keen at this time as that which arises from slight or indifference from persons of the opposite sex, and no experience will stir an individual so deeply as that which threatens to deprive him of the exclusive possession of the affections of the one he loves." Whatever the cause, I repeat, parents should never delay in combating repeated manifestations of jealousy, in order to make sure of preventing possible acts of extreme violence, subtle distortions of character that may persist through life, and neurotic maladies of gradual or rapid development. To bring home concretely to every parent who happens to read these lines the danger menacing his own jealous child in this last respect, I cannot do better than cite from real life a few instances of nervous trouble directly and demonstrably due to jealousy.