In one of the later books of the Çatapatha Brāhmaṇa (X. vi. 3) this ātman which has already arrived at a high degree of abstraction, is said to "pervade this universe." Brahma (neuter) in the Rigveda signified nothing more than "prayer" or "devotion." But even in the oldest Brāhmaṇas it has come to have the sense of "universal holiness," as manifested in prayer, priest, and sacrifice. In the Upanishads it is the holy principle which animates nature. Having a long subsequent history, this word is a very epitome of the evolution of religious thought in India. These two conceptions, Ātman and Brahma, are commonly treated as synonymous in the Upanishads. But, strictly speaking, Brahma, the older term, represents the cosmical principle which pervades the universe, Ātman the psychical principle manifested in man; and the latter, as the known, is used to explain the former as the unknown. The Ātman under the name of the Eternal (aksharam) is thus described in the Bṛihadāraṇyaka Upanishad (III. viii. 8, 11):—
"It is not large, and not minute; not short, not long; without blood, without fat; without shadow, without darkness; without wind, without ether; not adhesive, not tangible; without smell, without taste; without eyes, ears, voice, or mind; without heat, breath, or mouth; without personal or family name; unaging, undying, without fear, immortal, dustless, not uncovered or covered; with nothing before, nothing behind, nothing within. It consumes no one and is consumed by no one. It is the unseen seer, the unheard hearer, the unthought thinker, the unknown knower. There is no other seer, no other hearer, no other thinker, no other knower. That is the Eternal in which space (ākāça) is woven and which is interwoven with it."
