More than a century after his death in 1900, Nietzsche remains a seminal figure in the history of European intellectual life. Celebrated as a liberator by some, maligned as a pernicious influence by others, he was the subject of controversy during his lifetime, pursuing a hedonistic individualism and espousing concepts such as the Superman and the Will to Power until he died after a decade of institutionalized insanity. In this groundbreaking biography, Joachim Köhler seeks for the first time to understand Nietzsche's philosophy through a reconstruction of his inner life. In a revealing reinterpretation of his letters, diaries, and writings, Köhler shows that Nietzsche's suppressed homosexuality, generating a hatred of Christianity and conventional morality, was a central influence on his work. Further, Köhler argues, his philosophical position was fundamentally compromised by the concealment of his forbidden sexual desire. Throughout his life, the unhappy genius was also plagued by horrible nightmares, stemming from his much-loved father's death, which led to a profoundly disturbed conscience and an intense loathing of metaphysics. Seeking to disguise the truth of his innermost torments, Nietzsche contrived the persona of Zarathustra. The story of the great Persian philosopher, contends Köhler, reveals Nietzsche's own suppression and dionysiac liberation, and presents the culmination of his secret yearnings in the new myth of the Superman who, in his naked beauty, resembled the gods of classical Greece.