Khandogya-Upanishad: Eighth Prapathaka, Thirteenth Khanda

1. From the dark (the Brahman of the heart) I come to the nebulous (the world of Brahman), from the nebulous to the dark, shaking off all evil, as a horse shakes his hairs, and as the moon frees herself from the mouth of Rahu. Having shaken off the body, I obtain, self made and satisfied, the uncreated world of Brahman, yea, I obtain it.