" Nietzsche and Kierkegaard were the heralds of modern existentialism. They pioneered a mood of rebellion and dissatisfaction, created a new definition of existence as choice, action and self-assertion, and made a study of the anguish and difficulty of life. They also worked in the conviction that philosophy was not just a profession. It was life itself — the life of an individual. "

― Sarah Bakewell , At the Existentialist Café: Freedom, Being, and Apricot Cocktails