Anthony Storr writes both as a psychotherapist and as someone who is living in an age in which the destruction of the world is a distinct possibility. But the coin of aggression, as he shows, bears two faces. He discusses its normal role as a positive and natural drive, in the social structure of both animals and humans and its function in childhood, adult life and sexual relations; its negative aspect he considers in relation to hostility, depressive, schizoid, paranoid and psychopathic personalities. He closes with a plea - modest, humane and never Utopian - for attitudes and policies that in the long run might reduce hostility between peoples and between nations.