Ethical dualism or, as theorized by Descartes, between thought and extension. Ethical dualism on the other hand highlights the moral dimension instead or in addition to the metaphysical one, and envisions an inherent situation of conflict between two antagonistic forces, like light and darkness, Good and Evil. One of the most known and clear-cut interpretations of ethical dualism is the one conceptualized by Zoroastrianism, the ancient Persian religion, which bases its thought on the figure of the prophet Zoroaster (or Zarathustra), who claimed the existence of two original and contrasting principles, Ahura Mazda and Ahriman, respectively representing the forces of Good and
Thus Spoke Zarathustra of Silvaplana (close to Surlej); he was inspired by the sight of a gigantic, towering, pyramidal rock. Before "Zarathustra", Nietzsche had mentioned the concept in the fourth book of "The Gay Science" (e.g., sect. 341); this was the first public proclamation of the notion by him. Apart from its salient presence in "Zarathustra", it is also echoed throughout Nietzsche's work. At any rate, it is by Zarathustra's transfiguration that he embraces eternity, that he at last ascertains "the supreme will to power". This inspiration finds its expression with Zarathustra's roundelay, featured twice in the book, once near the story's close: