While in India the conception of the asura had veered more and more towards the dreadful and the dreaded, Zoroaster elevated it again - at the cost, indeed, of the daivas (daevas), whom he degraded to the rank of malicious powers and devils.
The very daevas are only the inferior instruments, the corrupted children of Ahriman, from whom come all that is evil in the world.
The daevas, unmasked and attacked by Zoroaster as the true enemies of mankind, are still, in the Gathas, without doubt the perfectly definite gods of old popular belief - the idols of the people.
In the later, developed system the daevas are the evil spirits in general, and their number has increased to millions.
The devil-worshippers, at their sacrifices, slay the ox; and this the daevas favour, for they are foes to the cattle and to cattlebreeding, and friends to those who work ill to the cow.