"...revenge. ...This reaction is still admired by most people, when the injury is great, and such as to arouse moral horror in disinterested people. Nor can it be wholly condemned, for it is one of the forces generating punishment, and punishment is something necessary. Moreover, from the point of view of mental health, the impulse to revenge is likely to be so strong that, if allowed no outlet, a man's whole outlook on life may become distorted and more or less insane."