Zurvanism and Later Sassanian Theological Debate

Zurvanism represents one of the most theologically significant internal developments within the Zoroastrian tradition, arising from an evident philosophical difficulty in the mainstream dualist scheme: if Ahura Mazda is the sole uncreated, supreme god, how can Angra Mainyu, his cosmic opposite, also exist as an independent principle without either compromising Ahura Mazda's absolute supremacy or making him, uncomfortably, the ultimate author of evil as well as good? The Zurvanite solution, first clearly attested in Greek sources from around the 4th century BCE (Eudemus of Rhodes, a pupil of Aristotle, reportedly described a Persian doctrine involving both Space and Time as primordial principles) but reaching its most developed form under the Sassanian dynasty (224–651 CE), posited Zurvan, "Time" (specifically Zurvan Akarana, "Infinite Time"), as a still more fundamental principle prior to and generative of both Ahura Mazda and Angra Mainyu, recasting them as twin sons of Zurvan rather than as the sole self-existent creator and his self-chosen adversary.