Irrational Man begins by discussing the roots of existentialism in the art and thinking of Augustine, Aquinas, Pascal, Baudelaire, Blake, Dostoevski, Tolstoy, Hemingway, Picasso, Joyce, and Beckett. The heart of the book explains the views of the foremost existentialists-Kierkegaard, Nietzsche, Heidegger, and Sartre. The result is a marvelously lucid definition of existentialism and a brilliant interpretation of its impact.