Zarathusthtra brought about important religious reform in Iran, giving a definitely moral character and direction to religion whilst at the same time preaching the doctrine of monotheism, which offered an eternal foundation of reality to goodness as an ideal of perfection. This volume provides a substantial introduction on the life and doctrines of Zarathushtra and compares the development of religion in India with that of Iran.
The Divine Songs of Zarathustra I – CXX.