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
Zoroaster 330 BCE. The Seleucid rulers who gained power following Alexander's death instituted an "Age of Alexander" as the new calendrical epoch. This did not appeal to the Zoroastrian priesthood who then attempted to establish an "Age of Zoroaster". To do so, they needed to establish when Zoroaster had lived, which they accomplished by (erroneous, some even identified Cyrus with Vishtaspa) counting back the length of successive generations, until they concluded that Zoroaster must have lived "258 years before Alexander". This estimate then re-appeared in the 9th- to 12th-century Arabic and Pahlavi texts of Zoroastrian tradition, like the 10th century Al-Masudi