Brahma Knowledge, by L. D. Barnett, , at sacred-texts.com
§ 5. Brahma and Prāṇa.—This conception, however it might be disguised in cosmogonic and mythopoeic forms, was in essence strictly materialistic. But by its side there arose in the schools of the Brāhmaṇas two somewhat different currents of thought—the doctrines of Brahma and of Prāṇa. Brahma, in the earlier Vedic books, is a neuter noun, meaning the spell or prayer of the priest and the magic power which it exerts over gods, men, and the universe. Prāṇa, again, is properly the breath of the body, hence the incorporeal forces or functional energies on which depends the existence of material life. Thus arose the idea of Force, cosmic power, Brahma, as the ultimate reality and origin of phenomenal being, the knowledge of which brought with it the knowledge of all the phenomena evolved from it.
Often the Upanishads, especially the older texts, identify Brahma (and the individual Self which is one with Brahma), with the "life-breath" in the microcosm and its analogue, the wind of the macrocosm. On the supremacy of
the breath over the other functions, see B.A. I. v. 14, Ch. I. xi. 5, v. i. 6 f., VI. vii., VII. xv., Pra. VI. 3 f.; breath or wind the guiding force of nature, B.A. I. v. 21 f., III. iii. 2, vii. 2 f.; first principle of nature, Kau. II. 12 f.
In the same mythological fashion Brahma is often symbolised by the manas, or organ of determinate sense-perception and will (see § 18), and by the ether, the macrocosmic analogue of the manas.
The earlier Upanishads often also speak of the cosmic principle as Purusha, literally "man." This term, as we have seen, arises from the Vedic hymn which mystically describes the origin of the world from the body of an ideal man sacrificed by the gods; hence it often denotes the Demiurge, or first principle of cosmic life (with a false etymology from puri-śaya, "lying in the city," viz. in the microcosmic and macrocosmic body), and sometimes is used loosely for spirit generally.
As the sun is sometimes mentioned as a symbol of Brahma, so also Brahma is sometimes typified macrocosmically by the purusha in the sun and microcosmically by the purusha in the eye (i.e. the reflected figure in the pupil).
Another symbol of Brahma as identified with the individual soul is the bodily heat (Ch. III. xiii. 7 f.). In Ch. IV. x.-xv. the sacred fires are identified with Brahma, to which are given the especial attributes of space (kham) and joy (kam). See further §§ 8, 22.