" Two such misfits in the nineteenth century had a particularly strong influence on the later existentialists: Søren Kierkegaard and Friedrich Nietzsche. Neither was an academic philosopher: Kierkegaard had no university career, and Nietzsche was a professor of Greek and Roman philology who had to retire because of ill health. Both were individualists, and both were contrarians by nature, dedicated to making people uncomfortable. Both must have been unbearable to spend more than a few hours with. Both sit outside the main story of modern existentialism, as precursors, but had a great impact on what developed later. "

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