linguistic:voice_change, linguistic:translation
Chandogya Upanishad

The Chandogya Upanishad is one of the oldest Upanishads of Hinduism. It opens with the recommendation that "let a man meditate on Om". It calls the syllable Om as udgitha (उद्गीथ; song, chant), and asserts that the significance of the syllable is thus: the essence of all beings is earth, the essence of earth is water, the essence of water are the plants, the essence of plants is man, the essence of man is speech, the essence of speech is the Rigveda, the essence of the Rigveda is the Samaveda, and the essence of Samaveda is the udgitha (song, Om).

Ṛc (ऋच्) is speech, states the text, and sāman (सामन्) is breath; they are pairs, and because they have love for each other, speech and breath find themselves together and mate to produce a song. The highest song is Om, asserts section 1.1 of Chandogya Upanishad. It is the symbol of awe, of reverence, of threefold knowledge because Adhvaryu invokes it, the Hotr recites it, and Udgatr sings it.

The second volume of the first chapter continues its discussion of syllable Om, explaining its use as a struggle between Devas (gods) and Asuras (demons). Max Muller states that this struggle between gods and demons is considered allegorical by ancient Indian scholars, as good and evil inclinations within man, respectively. The legend in section 1.2 of Chandogya Upanishad states that gods took the Udgitha (song of Om) unto themselves, thinking, "with this song we shall overcome the demons". The syllable Om is thus implied as that which inspires the good inclinations within each person.

Chandogya Upanishad's exposition of syllable Om in its opening chapter combines etymological speculations, symbolism, metric structure and philosophical themes. In the second chapter of the Chandogya Upanishad, the meaning and significance of Om evolves into a philosophical discourse, such as in section 2.10 where Om is linked to the Highest Self, and section 2.23 where the text asserts Om is the essence of three forms of knowledge, Om is Brahman and "Om is all this ".