Khândogya Upanishad: VIII, 14

FOURTEENTH KHANDA. 1. He who is called ether 3 (âkâsa) is the revealer of all forms and names. That within which these forms and names are contained is the Brahman, the Immortal, the Self. I come to the hall of Pragâpati, to the house; I am the glorious among Brahmans, glorious among princes, glorious among men 4. I obtained that glory, I am glorious among the glorious. May I never go to the white, toothless, yet devouring, white abode 5; may I never go to it. 143:3 Âkâsa, ether or space, is a name of Brahman, because, like ether, Brahman has no body and is infinitely small. 143:4 Here the three classes, commonly called castes, are clearly marked by the names of brâhmana, râgan, and vis. 143:5 Yonisabditam pragananendriyam.