No single superior intelligence, no great Principle of Evil, was placed at their head.

Ahriman (Angro-mainyus) does not occur in the Gathas as a proper name.

Far less is there any graduated hierarchy of evil, surrounding a Prince of Darkness, with a sort of court, antagonistic to the angelic host of Ormazd, as in the latter portions of the Zendavesta and in the modern Parsee system.
Thus Dualism proper, or a belief in two uncreated and independent principles, one a principle of good and the other a principal of evil, was no part of the original Zoroastrianism.

At the same time we find, even in the Gathas, the earliest portions of the Zondavesta, the germ out of which Dualism sprung.

The contrast between good and evil is strongly and sharply marked in the Gathas; the writers continually harp upon it, their minds are evidently struck with this sad antithesis which colors the whole moral world to them; they see everywhere a struggle between right and wrong, truth and falsehood, purity and impurity; apparently they are blind to the evidence of harmony and agreement in the universe, discerning nothing anywhere but strife, conflict, antagonism.