Tasya vacakah pranavah
He is represented by the sacred syllable AUM, called pranava. Pranava stands for praise of the divine and fulfillment of divinity.
In the Upanishads, which are the oldest philosophical texts in India, AUM is the prime means to attain Brahman, which denotes the universal consciousness. Everything in the world is vibration, so is sound. The Hindus believe that when the creation began, the divine took the form as the first and original vibration manifesting as sound AUM. As such, through its subtle form, AUM sound vibrations, we can connect to the divine, the source. The Katha Upanishad says in 2.16, “Brahman is known through the sacred syllable AUM. Since Brahman is AUM, when AUM is known, Brahman is known”.
AUM is composed of three syllables, A, U, M. “A” represents creation, waking state and Brahma; “U” represents preservation, dreaming state, and Vishnu; “M” represents destruction, dreamless sleep and Shiva. The silence after chanting “AUM” represents the fourth state, Turiya, which is the absolute reality, pure consciousness and Brahman. Meditation on AUM leads Sadhaka to experience the true Self.
The three letters A, U, M also represent the three genders: masculine, feminine and neuter; the three gunas: sattva, rajas, and tamas; the three aspects of time: past, present and future; and the three gurus: mother, father and preceptor; speech (vak), mind (manas), and life force (prana). AUM is the symbol of divinity and omnipotence.
Meditation on AUM can be done in three steps. Firstly, AUM is chanted with devotion for at least 15 minutes continuously daily. Sadhaka is to focus on the sound vibrations and feel the stillness of mind. Secondly, chant AUM mentally. This step is more powerful than the first step, because we need to focus on the mind all the time. We can practice this while doing pranayama or sitting alone. The last step is to let AUM come back to us. Sit still with eyes closed, listen to all sounds from the surroundings and try to hear the AUM sound, which is formed by merging all the other sounds. As mentioned earlier, as we hear AUM, we hear the Supreme. Then the ego is gone, the outcome becomes irrelevant, and we reach the fourth state of Turiya. In this state, we are connected to the highest universal energy, as such, we obtain pure knowledge and omniscience from the Source. This knowledge is accessible at any time, any place.