Aitareya-Aranyaka: Second Aranyaka, Third Adhyâya, Seventh Khanda
1. “This (nishkevalya-sastra) becomes perfect as a thousand of Brihatîs. It is glory (the glorious Brahman, not the absolute Brahman), it is Indra. Indra is the lord of all beings. He who thus knows Indra as the lord of all beings, departs from this world by loosening the bonds of life”—so said Mahidasa Aitareya. Having departed he becomes Indra (or Hiranyagarbha) and shines in those worlds.
2. And with regard to this they say: “If a man obtains the other world in this form (by meditating on the prâna, breath, which is the uktha, the hymn of the mahâvrata), then in what form does he obtain this world?”
3. Here the blood of the woman is a form of Agni (fire); therefore no one should despise it. And the seed of the man is a form of ditya (sun) therefore no one should despise it. This self (the woman) gives her self (skin, blood, and flesh) to that self (fat, bone, and marrow), and that self (man) gives his self (fat, bone, and marrow) to this self (skin, blood, and flesh). Thus these two grow together. In this form (belonging to the woman and to fire) he goes to that world (belonging to the man and the sun), and in that form (belonging to man and the sun) he goes to this world (belonging to the woman and to fire).