Om

Om, also written Aum and called Pranava, is revered as the primordial cosmic vibration from which the entire universe is said to have manifested. The syllable already appears throughout the Rig Veda and other Vedic Samhitas as an invocatory utterance placed before sacred recitation. It opens and closes Vedic recitation and prefaces most Sanskrit mantras. In Vedantic teaching it stands as the sound-symbol of Brahman itself, the one syllable through which the formless absolute is approached by the mind and voice.

The fullest scriptural treatment of Om is the Mandukya Upanishad, a short Upanishad of twelve verses devoted entirely to this single syllable. Its opening verse (1) declares, Om ityetad aksharam idam sarvam: this syllable Om is all this. Whatever has existed, exists, or will exist is nothing other than Om, and whatever lies beyond the three times is also, in essence, Om. Verses eight through eleven then map the syllable's three phonemes — A, U, and M — onto the three ordinary states of consciousness. Verse twelve then points beyond all three to a fourth, silent state the Upanishad calls Turiya.

The first phoneme, A, corresponds to Vaishvanara, the waking state, in which the self knows the gross physical universe through the five senses; its resonance is felt low, near the navel. The second, U, corresponds to Taijasa, the dreaming state, the subtle inner world of thought, imagination, and memory, resonating in the chest and throat. The third, M, corresponds to Prajna, the state of deep, dreamless sleep. It is a causal state of seed potential where even the mind's activity has withdrawn into undifferentiated rest, felt in the nasal cavity, the forehead, and the crown. Beyond these three sounded phonemes, the Upanishad places a fourth, soundless quarter, Amatra, the silence into which the hum of M finally dissolves. This is Turiya, pure undivided awareness, the unmanifest witness of waking, dreaming, and deep sleep alike. The text identifies Turiya with the Atman, the Self that is one with Brahman.

Because the Upanishad itself is so compressed, its teaching reached later generations largely through the Mandukya Karika, a verse commentary attributed to the sixth-century teacher Gaudapada. Gaudapada draws out the Upanishad's logic in full, arguing that Turiya alone is real and that the three ordinary states are superimpositions upon it, much as a dream is superimposed upon the waking mind. This reading became foundational for Advaita Vedanta, the nondual philosophy that Gaudapada's own disciple's disciple, Adi Shankaracharya, would later systematize across the broader Upanishadic corpus. Shankaracharya himself wrote a commentary on both the Upanishad and the Karika, cementing Om's place at the center of Vedantic metaphysics.

Beyond Vedanta, Om carries equal weight in classical yoga. Patanjali's Yoga Sutra identifies Pranava as the verbal expression of Ishvara, the Lord, and prescribes its repetition as a direct path to one-pointed concentration. The Bhagavad Gita (8.13) likewise calls Om the single-syllable Brahman and recommends it be uttered, together with remembrance of the divine, at the moment of death. The Gita (17.23) also pairs it with the closing invocation Om Tat Sat, spoken at the end of every sacred undertaking. In daily practice, Om is chanted as three long, deliberate sounds. The mouth opens wide for an "aaa" felt at the navel, narrows into an "ooo" felt rising through the chest and throat, and finally closes into a humming "mmm" felt at the crown. Practitioners then rest in the silence that follows, treating it as the chant's true culmination rather than a mere pause.

Though the Mandukya Upanishad gives Om its most systematic exposition, the conviction that ultimate reality can be distilled into a single primordial sound recurs elsewhere in Indian religion. The Buddhist mantra Om Mani Padme Hum and the Sikh invocation Ik Onkar each affirm, in their own idiom, that the divine is one and that sound itself can carry a seeker toward it. Within Sanatana Dharma, Om remains the first sound placed before scripture, worship, and meditation alike, the syllable through which the manifest world is said to return, quarter by quarter, to its unmanifest source.