The word ātman stems from the Sanskrit root āt-, “to breathe.” Ātman may be translated in various ways: breath of life, core essential self, life source, soul, living being, or highest self. One of the earliest references to ātman or self can be found in Ṛgveda 10.121 (c. 1500 BCE), which indicates a link between Prajāpati, the creator principle, and the self:
In the beginning Prajāpati stirred and evolved.
Once born he was the Lord of every being;
this heaven and earth did he sustain
Giver of life (ātman), giver of strength
Whose shadow is immortality,
whose shadow is death. (ṚV. 10.121, 1–…