In the Hindu symbology the 'OM' is the most pronounced sacred sound-symbol or nada-brahman. All the Vedic mantras are product of this monosyllable which, it is believed, existed before the world was created. Thus "OM" is referred to as the supreme mantra of Hindu scriptures.

Katha Upanishad has explained the very essence of this supreme mantra. It says that 'The goal which all the Vedas declare, which all austerities aim at, and which men desire when they lead the life of continuance, I will tell you briefly: it is OM. This syllable OM is indeed Brahman. This syllable is the Highest. Whosoever knows this syllable obtains all he desires. This is the best support; this is the highest support. Whosoever knows this support is adored in the world of Brahma."

In order to understand the meaning, purpose and mysticism of OM, one should delve into it philosophically. According to the Hindu philosophy the world of the Universe had Nama (name) and Rupa (shape) which are the conditions of manifestations. Swami Vivekananda had perfectly analysed the theme as he wrote, "In the human microcosm, there cannot be a single wave in the mind-stuff ( chittavritti) unconditioned by name and form. If it be true that nature is built throughout on the same plan, this kind of conditioning by name and form must also be the plan of the building of the whole of the cosmos...The body is the form, and the mind or the antahkarana is the name, and sound-symbols are universally associated with nama (name) in all beings having the power of speech. In the individual man the thought-waves rising in the limited Mahat or Chitta (Mind-stuff) must manifest themselves, first as words, and then as the more concrete forms."

Likewise, the creator of the Universe Brahma or Cosmic mahat first manifested himself as the name and then as the form of universe. However, behind this there is an inseparable Sphota, the manifestor of World. Swamiji further wrote that 'This Sphota has one word as its only possible symbol, and this is the OM. And as by no possible means of analysis can we separate the word from the idea, this OM and the eternal Sphota are inseparable...The sphota is the material of the words, yet it is not any definite state. This is to say, if all peculiarities which distinguished one word from another be removed, then what remains will be the sphota; therefore this sphota is called Nada-Brahman, the sound Brahman."' Thus the OM which is Nada-Brahman or Sphota is the holiest symbol of Hinduism. OM encompasses all the aspects and angles of the creative power and has no substitute. Thus this monosyllable mantra is crowned as supreme in the Vedic scriptures.

Regarding the origin and manifestation of OM the seers of Atharvaveda explain that 'The super being created Brahman, the creator, on the Lotus. Having begun to think 'by which single syllable may I be able to enjoy the desire, all the worlds, all the Gods, all the Vedas, all the sacrifices, all the sounds, all the beings stationary and moving'. He practised self-control and saw this OM. ..the all-pervading, omnipresent, the eternally potent Brahma, the Brahma's own symbolic syllable of which the presiding divinity is Brahman itself, with it he enjoyed all the desires of all the worlds, all the Gods, all the Vedas, all the sacrifices, all the sounds, all the remarks, and all the beings...Therefore, the Brahman who, desiring whatever we want, fasts (of) three nights, sits on sacred grass facing east and keeps under control his tongue and repeats this imperishable OM, for him all objects are realised successfully!". Let us try to understand the mantra OM's mysticism and its sound aspect. When OM is pronounced we utter three letters AUM. The letter A has its own singular entity on the score of phonetics. And if A U M is coupled together, the sound is created from the root within the mouth, and the U exactly represents the rolling forward impulses created from A and end up in the lips with the letter M If the OM or AUM is pronounced correctly it covers the whole phonetics of speech of mankind. Thus OM is regarded as the eternal bliss and truly symbolises the God.

Manduka Upanishadhad correctly interpreted the inner meaning of this OM-the Nada-Brahman. It says that "OM is the bow; one's self is arrow; the Brahman, it is said, is the target. One should shoot with all attention and like the arrow he will become one with it."

Likewise, the whole Vedic scripture is studded with one sound, the OM, which has an inseparable name and shape, which is the cause of creation and has a scientific definition of all that man's speech could express.