In Friedrich Nietzsche's classic philosophy tome, Thus Spoke Zarathustra, Zarathustra is the central prophet. He left home at age 30 to live in the forests and caves in seclusion, until a decade later he returns to the land of the humans, brimming with wisdom and joy. He espouses various ideas such as the death of God, the transitioning from animal to man to superman, and the concept of the superman as the one who has surpassed all of the inhibitions of modern man.