In the Vedas the mantra (sound) is the primary source from which the universe has sprung; it is the primordial vibration presents in everything, the motor of the universe. Through the study and the search on the mantras the ancient wise man has discovered how we can be in harmony with the cosmos and with ourselves.
ॐ (Aum)It is the primordial sound, is the matrix of all that exists in the universe. It doesn't have a particular meaning; it is rather a sacred syllable that represents the essence of the vital energy from which the creation has sprung. ॐ is the combination of three sounds: A - U - M.
The A represents Brahma the creator, the conscience, the state of vigil.
The U represents Vishnu the preserver, the subconscious, the state of dream.
The M represents Shiva the destroyer, the unconscious, the state of deep sleep.
It can be noticed as these three letters are tightly correlated with the endless breath of the universe, in which the three strengths of creation, preservation and destruction continually follow one another and how they are correlated with the three dimensions of the human conscience.
The utilization of the sounds for spiritual purpose is universally used. In a lot of religions the continuous repeating of a sentence or a sacred sound with the help of a rosary (japa mala) represents the highest form of meditation. The mantras are the best vehicle in the meditation because through them the mind calms the incessant flow of thoughts and it settles in a state of deep concentration.