The Indestructible Syllable
Om is the single syllable representing Brahman, the ultimate reality.
Om (Aum) is the primordial sound, the verbal symbol of ultimate reality. Chanting Om aligns the practitioner with cosmic vibration. The three phonemes (A-U-M) represent creation, preservation, and dissolution; waking, dreaming, and deep sleep; and other trinities. The Mandukya Upanishad devotes its twelve verses to expounding these three sounds and the silence beyond them. This sacred syllable serves as both object of meditation and verbal gateway to the infinite.
I am the syllable Om in all the Vedas.
Mandukya Upanishad states that Om alone is this whole universe—past, present, future, and beyond time. It is the sound of reality itself.
Bhagavad Gita