The Sama Veda, the poetical Veda, orthographically maps Om to the audible, the musical truths in its numerous variations (Oum, Aum, Ovā Ovā Ovā Um, etc.) and then attempts to extract musical meters from it.The syllable Om evolves to mean many abstract ideas in the earliest Upanishads.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 Rig Veda, the essence of the Rig Veda is the Sama Veda, and the essence of Sama Veda is the udgitha (song, Om).
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 Bhagavad Gita, in the Epic Mahabharata, mentions the meaning and significance of Om in several verses.For example, Fowler notes that verse 9.17 of the Bhagavad Gita synthesizes the competing dualistic and monist streams of thought in Hinduism, by using "Om which is the symbol for the indescribable, impersonal Brahman".Max Müller and other scholars state that these philosophical texts recommend Om as a "tool for meditation", explain various meanings that the syllable may be in the mind of one meditating, ranging from "artificial and senseless" to "highest concepts such as the cause of the Universe, essence of life, Brahman, Atman, and Self-knowledge". When occurring within spoken Sanskrit, the syllable is subject to the normal rules of sandhi in Sanskrit grammar, however with the additional peculiarity that after preceding a or ā, the au of aum does not form vriddhi (au) but guna (o) per Pāṇini 6.1.95 (i.e. It is sometimes also written ओ३म् (o̿m ), notably by Arya Samaj, where ३ (i.e., the digit "3") is pluta ("three times as long"), indicating a length of three morae (that is, the time it takes to say three syllables) — an overlong nasalised close-mid back rounded vowel.
The Om symbol is a ligature in Devanagari, combining ओ (au) and chandrabindu (ँ, ṃ).For example, it is called Unalom or Aum in Thailand and has been a part of various flags and official emblems such as in the Thong Chom Klao of King Rama IV (r. There have been proposals that the Om syllable may already have had written representations in Brahmi script, dating to before the Common Era.A proposal by Deb (1848) held that the swastika is "a monogrammatic representation of the syllable Om, wherein two Brahmi /o/ characters ( Om came to be used as a standard utterance at the beginning of mantras, chants or citations taken from the Vedas.The Katho Upanishad is the legendary story of a little boy, Nachiketa – the son of sage Vajasravasa – who meets Yama, the Indian deity of death.Their conversation evolves to a discussion of the nature of man, knowledge, Atman (Soul, Self) and moksha (liberation). Taking as a bow the great weapon of the Upanishad, one should put upon it an arrow sharpened by meditation, Stretching it with a thought directed to the essence of That, Penetrate that Imperishable as the mark, my friend.For example, the Gayatri mantra, which consists of a verse from the Rigveda Samhita (RV 3.62.10), is prefixed not just by Om but by Om followed by the formula bhūr bhuvaḥ svaḥ.