Angra Mainyu
In 1884, Martin Haug proposed a new interpretation of "Yasna" 30.3 that subsequently influenced Zoroastrian doctrine to a significant extent. According to Haug's interpretation, the "twin spirits" of 30.3 were Angra Mainyu and Spenta Mainyu, the former being literally the "Destructive Spirit" and the latter being the "Bounteous Spirit" (of Ahura Mazda). Further, in Haug's scheme, Angra Mainyu was now not Ahura Mazda's binary opposite, but—like Spenta Mainyu—an emanation of Him. Haug also interpreted the concept of a free will of "Yasna" 45.9 as an accommodation to explain where Angra Mainyu came from since Ahura Mazda created only good. The free will made it possible for Angra Mainyu to "choose" to be evil. Although these latter conclusions were not substantiated by Zoroastrian tradition, at the time Haug's interpretation was gratefully accepted by the Parsis of Bombay since it provided a defense against Christian missionary rhetoric, particularly the attacks on the Zoroastrian idea of an uncreated Evil that was as uncreated as God was. Following Haug, the Bombay Parsis began to defend themselves in the English-language press, the argument being that Angra Mainyu was not Mazda's binary opposite, but his subordinate, who—as in Zurvanism also—"chose" to be evil. Consequently, Haug's theories were disseminated as a Parsi interpretation, also in the West, where they appeared to be corroborating Haug. Reinforcing themselves, Haug's ideas came to be iterated so often that they are today almost universally accepted as doctrine.