Quote
"In the beginning this world was the self (atman), one alone, and there was no other being at all that blinked an eye."

Aitareya Upanishad
Aitareya Upanishad
The Aitareya Upanishad is a Mukhya Upanishad, associated with the Rigveda. It comprises the fourth, fifth and sixth chapters of the second book of Aitareya Aranyaka, which is one of the four layers of Rig vedic text.
"In the beginning this world was the self (atman), one alone, and there was no other being at all that blinked an eye."
"Knowledge is the eye of all that,"
"It is with this self consisting of knowledge that he went up from this world"