The disappearance of personal hate from the world can only come when men realize the essential unity of mankind. For part of the psychological origin of hate lies in unlikeness. Great unlikeness in color and facial line seems to act as a challenge to the feeling of superiority. Wherever a "different" group challenges another's superiority, or enters into active competition for the goods of life, there hate enters in its most virulent form. The disappearance of the "unlike" feeling is very slow and is hindered by the existence of small "particular" groups. Little nationalities,[1] small sects, even exclusive clubs and circles are means of generating difference and thus hate. [1] The more nationalities, each with its claim to a great destiny, the more wars! There is the essential danger and folly of tribal patriotism. We shall not enter into the origin of hate through the danger to purpose, through rivalry among those not separated by unlikeness. Hate seems to be a chronic anger, or at least that emotion kept at a more or less constant level by perception of danger and the threat at personal dignity and worth. Obstructed love or passion and the feeling of "wrong," i. e., injury done that was not merited, that the personal conscience does not justify, furnish the most virulent types of hatred. "Love thine enemies" is still an impossible injunction for most men. We cannot hope to trace the feeling of revenge in its effects on human conduct. Though at present religion and law both prohibit revengeful acts, the desire "to get even" flames high in almost every human breast under all kinds of injury or insult. This form of hate may express itself crudely in the vendetta of the Sicilian, the feud of the Tennessee mountaineer, or the assault and battery of an aggrieved husband; it is behind the present-day conflict in Ireland, and it threatened Europe for forty years after the Franco-Prussian War, --and no man knows how profoundly it will influence future world affairs because of the Great War. Often it disguises itself as justice, the principle of the thing, in those who will not admit revenge as a motive; and the eclipsed and beaten take revenge in slander, innuendo and double-edged praise. To some revenge is a devil to be fought out of their hearts; to others it is a god that guides every act. We may define nobility of character as the withdrawal from revenge as a motive and the substitution for it of justice.