human
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.