The Persians borrow the idea of Varuna Asura, whose eye is the sun.

They spiritualize this, and create an Asura unknown to other nations.
Of von Bradke's attempt to prove an original Dyaus Asura we have said nothing, because the attempt has failed signally.

He imagines that the epithet Asura was given to Dyaus in the Indo-Iranian period, and that from a Dyaus Pitar Asura the Iranians made an abstract Asura, while the Hindus raised the other gods and depressed Dyaus Pitar Asura; whereas it is quite certain that Varuna (Asura) grew up, out, and over the other Asuras, his former equals.
And yet it is almost a pity to spend time to demonstrate that Varuna-worship was not monotheistic originally.

We gladly admit that, even if not a primitive monotheistic deity, Varuna yet is a god that belongs to a very old period of Hindu literature.

And, for a worship so antique, how noble is the idea, how exalted is the completed conception of him! Truly, the Hindus and Persians alone of Aryans mount nearest to the high level of Hebraic thought.