The basis of tragedy is man's helplessness against disease, war and death; the basis of comedy is man's helplessness against vanity (the vanity of love, greed, lust, power).
Bio: Martin E. P. "Marty" Seligman is an American psychologist, educator, and author of self-help books. Since the late 90's, Seligman has been an avid promoter within the scientific community for the field of positive psychology.