Yoga Sutra 1:27 - Aum

1:27

Tasya vachakah pranavah तस्य वाचकः प्रणव 

The sacred word designating this creative source is the sound ॐ, called Pranava.

A scientific study has shown that chanting Aum for about 15 minutes everyday increases theta waves in your brain. When theta waves are predominant your mind is quiet and peaceful. A newborn baby has the most theta waves in her brain. Chanting and meditating on Aum, brings your brain in the state of a newborn baby, no thoughts, no likes or dislikes, no stress, just being!

Theta is the border between the conscious and the subconscious world, and by learning to use a conscious, waking Theta brain wave we can access and influence the powerful subconscious part of ourselves that is normally inaccessible to our waking minds. While in the Theta state, the mind is capable of deep and profound learning, healing, and growth - it is the brain wave where our minds can connect to the Divine and manifest changes in the material world.

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Aum is composed of three syllables, a, u, m. Without these three sounds, no word can begin, resound or end in any language. these three sounds are universal, they are the seed (bija) of all words.

The letters, a, u, m symbolizes speech (vak), mind (manas) and the breath of life (prana). As leaves are held together by a twig, all speech is held together by aum. Aum is the everlasting spirit, a symbol of serenity, divinity, majestic power, omnipotence and universality.

Aum as a whole stands for the realization that liberates the human spirit from the confines of body, mind, intellect and ego. By meditating upon Aum, the sadhaka remains steady, pure, and faithful. He becomes a great soul (mahatma). He finds the presence of Supreme Spirit within, and earns the peace which is free from fear, dissolution and death.

~ B. K. S Iyengar

"Om 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"

~Mandukya Upanishad

"The goal which all the Vedas declare, which all austerities aim at, and which men desire when they lead the life of continence … is Om. This syllable Om is indeed Brahman. Whosoever knows this syllable obtains all that he desires. This is the best support; this is the highest support. Whosoever knows this support is adored in the world of Brahma."
~ Katha Upanisha