The self-overcoming of morality, out of truthfulness; the self-overcoming of the moralist, into his opposite — into me — that is what the name of Zarathustra means in my mouth.
Nietzsche presents self-overcoming as the dialectical movement by which morality destroys itself through its own supreme virtue — truthfulness — thereby identifying Zarathustra as the incarnation of this self-canceling process.
, On the Genealogy of Morals, 1887thesis