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: Susan Cain is an American writer and lecturer, and author of the 2012 non-fiction book Quiet: The Power of Introverts in a World That Can't Stop Talking, which argues that modern Western culture misunderstands and undervalues the traits and capabilities of introverted people.