The Religion and Philosophy of the Veda and Upanishads v1.c18.s1.18

v1.c18.s1.18

In the third place Agni has a birth in the heaven; he is born there and was brought down by Mātariçvan, who is doubtless his lightning form. The Aitareya Brāhmaṇa⁶ calls him at once heavenly and in the waters. Agni, however, is often as the god contrasted with the lightning. Agni as heavenly is the sun, born in the morning. The Aitareya⁷ says that on setting the sun enters into Agni, and in the Rigveda⁸ Agni unites himself with the rays of the sun. But this side of the nature of Agni is little referred to: the sun was too great and prominent a deity to be treated merely as a form of Agni.