
Aum is said to be the essence of all mantras, the highest of all matras or divine word (shabda), brahman (ultimate reality) itself. Aum is said to be the essence of the Vedas.
By sound and form, AUM symbolizes the infinite Brahman (ultimate reality) and the entire universe.
A stands for Creation; U stands for Preservation; M stands for Destruction or dissolution.
This is representative of the Trinity of God (Brahma, Vishnu and Shiva).
The three portions of AUM relate to the states of waking, dream and deep sleep and the three gunas (rajas, satva, tamas) The three letters also indicates three planes of existence, heaven (swarga), earth (martya) and netherworld (patala).
All the words produced by the human vocal organ can be represented by AUM. A is produced by the throat, U & M by the lips In the Vedas, AUM is the sound of the Sun, the sound of Light. It is the sound of assent (affirmation) and ascent (it has an upward movement and uplifts the soul, as the sound of the divine eagle or falcon.
It is a mantra or prayer in itself. If repeated with the correct intonation, it can resonate throughout the body so that the sound penetrates to the centre of one's being, the atman or the soul.
The Eternal Syllable:
According to the मंदुक्य उपनिषद् "ॐ is the one eternal syllable of which all that exists is but the development. The past, the present, and the future are all included in this one sound, and all that exists beyond the three forms of time is also implied in it".
The Vision of Om:
Om provides a dualistic viewpoint. On one hand, it projects the mind beyond the immediate to what is abstract and inexpressible. On the other hand, it makes the absolute more tangible and comprehensive. It encompasses all potentialities and possibilities; it is everything that was, is, or can yet be. It is omnipotent and likewise remains undefined.
The Power of ॐ :
While meditating , when we chant Om, we create within ourselves a vibration that attunes sympathy with the cosmic vibration and we start thinking universally. The momentary silence between each chant becomes palpable. Mind moves between the opposites of sound and silence until, at last, it ceases the sound. In the silence, the single thought—Om—is quenched; there is no thought. This is the state of trance, where the mind and the intellect are transcended as the individual self merges with the Infinite Self in the pious moment of realization. It is a moment when the petty worldly affairs are lost in the desire for the universal. Such is the immeasurable power of Om.