Zarathustra was the first to consider the fight of good and evil the very wheel in the machinery of things: the transposition of morality into the metaphysical realm, as a force, cause, and end in itself, is his work. [...] Zarathustra created this most calamitous error, morality; consequently, he must also be the first to recognize it.

On the Genealogy of Morals (ed. Vintage, 1989) - ISBN: 9780679724629