Thus Spoke Zarathustra: A Book for All and None is a philosophical novel by German philosopher Friedrich Nietzsche, composed in four parts written between 1883 and 1885 and published between 1883 and 1891.

Nietzsche spoke of "the death of God," and foresaw the dissolution of traditional religion and metaphysics. Some interpreters of Nietzsche believe he embraced nihilism, rejected philosophical reasoning, and promoted a literary exploration of the human condition, while not being concerned with gaining truth and knowledge in the traditional sense of those terms. However, other interpreters of Nietzsche say that in attempting to counteract the predicted rise of nihilism, he was engaged in a positive program to reaffirm life, and so he called for a radical, naturalistic rethinking of the nature of human existence, knowledge, and morality. On either interpretation, it is agreed that he suggested a plan for “becoming what one is” through the cultivation of instincts and various cognitive faculties, a plan that requires constant struggle with one’s psychological and intellectual inheritances.