Chandogya Upanishad: ( 30/03/2013. )

Chapter II — Meditation on Om as the Prana   1.   When the gods and the demons, both offspring of Prajapati,  fought with each other, the gods took hold of the Udgitha,  thinking that with this they would vanquish the demons.   2.   They (i.e. the gods) meditated on the Udgitha (Om) as the  prana which functions through the nose. But the demons  pierced it (i.e. the prana) with evil. Therefore with it (i.e. the  breath) one smells both what is pleasant—smelling and what is  foul—smelling. For the breath is pierced by evil.   3.   Then they meditated on the Udgitha as speech. But the demons  pierced it with evil. Therefore one speaks both truth and  falsehood. For speech is pierced by evil.   4.   Then they meditated on the Udgitha as the eye. But the demons  pierced it with evil. Therefore one sees both what is sightly and  what is unsightly. For the eye is pierced by evil.   5.   Then they meditated on the Udgitha as the ear. But the demons  pierced it with

Chapter I — Meditation on Om   1.   The syllable Om, called the Udgitha, should be meditated upon;  for people sing the Udgitha, beginning with Om.  Now follows the detailed explanation of the syllable:   2.   The essence of all these beings is the earth; the essence of the  earth is water; the essence of water is plants; the essence of  plants is a person; essence of a person is speech; the essence of  speech is the Rig—Veda; essence of the Rig—Veda is the  Sama—Veda; the essence of the Sama—Veda is the Udgitha  which is Om.   3.   That Udgitha (Om) is the best of all essences, the supreme,  deserving the highest place, the eighth.   4.   What, then, is the Rik? What is the Saman? What is the  Udgitha? This is to be considered.   5.   Speech, indeed, is the Rik; the vital breath (prana) is the  Saman; the syllable Om is the Udgitha. Speech and the prana,  or the Rik and the Saman, form a couple.   6.   And that couple become united in the syllable Om. Whe

Invocation   Om. May the different limbs of my body, my tongue, prana,  eyes, ears and my strength and also all the other sense—organs  be nourished! All, indeed, is Brahman, as is declared in the  Upanishads. May I never deny Brahman! May Brahman never  deny me! May there never be denial on my part! May all the  virtues described in the Upanishads belong to me, who am  devoted to Atman! Yea, may they all belong to me!  Om. Peace! Peace! Peace!