Asura is a god within, a god of chiefly spiritual and moral character. Now in the later development — in the later parts of the Rigveda — Asura disintegrated into a multitude of asuras, and they are demons of a definitely evil nature.
Jung traces the devolution of Asura from a supreme inward deity of spiritual-moral authority in the early Rigveda to a proliferating company of malevolent demons, linking this fragmentation to the Iranian transformation via Ahura Mazda.
, Nietzsche’s Zarathustra: Notes of the Seminar Given in 1934-1939, 1988thesis