Turiya

Upanishads

Turiya as 'the fourth' is referred to in a number of principal Upanishads. One of the earliest mentions of the phrase turiya, "fourth", is in verse 5.14.3 of the Brihadaranyaka Upanishad, referring to a 'fourth foot' of the Gayatri Mantra, the first, second and third foot being the 24 syllables of this mantra:

Then there is that fourth (turiya) vivid foot of the Gayatri, which is none other than the sun blazing beyond the sky. The term turiya means the same thing as 'fourth'(caturtha). 'Vivid foot' for the sunblazes beyond the entire expanse of the sky. A man who knows this foot of the Gayatri in this way will likewise blaze with splendour and fame.

According to Raju, chapter 8.7 through 8.12 of the Chandogya Upanishad, though not mentioning turiya, 'anticipate' the Mandukya Upanishad and it's treatment of turiya. These verses of the Chandogya Upanishad set out a dialogue between Indra and Virocana, in search of atman, the immortal perceiver, and Prajapati, their teacher. After rejecting the physical body, the dream self, and the dreamless sleep (in which there is no perception of "I am") as atman, Prajapati declares in verse 12 to Indra that the mortal body is the abode of the "immortal and non-bodily self", which is the perceiver, the one who perceives due to the faculties of the senses.

The phrase "turiya" also appears in Maitri Upanishad in sections 6.19 (in the context of yoga) and 7.11:

Now, it has elsewhere been said: 'Verily, when a knower has restrained his mind from the external, and the breathing spirit (prāṇa) has put to rest objects of sense, there-upon let him continue void of conceptions. Since the living individual (jīva) who is named "breathing spirit" has arisen here from what is not breathing spirit, therefore, verily, let the breathing spirit restrain his breathing spirit in what is called the fourth condition (tiwya)' For thus has it been said:-

That which is non-thought, [yet] which stands in the midst of thought,
The unthinkable, supreme mystery! —
Thereon let one concentrate his thought

And the subtle body (linga), too, without support.

— Maitri Upanishad, Section 6.19

7.11: He who sees with the eye, and he who moves in dreams,

He who is deep asleep, and he who is beyond the deep sleeper —
These are a person's four distinct conditions.

Of these the fourth (turya) is greater [than the rest].

— Maitri Upanishad, Section 7.11

Verse 7 of the Mandukya Upanishad refers to "the fourth" (caturtha), or "the fourth quarter", the first, second and third quarter being situated in the waking, dreaming and dreamless state:

They consider the fourth quarter as perceiving neither what is inside nor what is outside, nor even both together; not as a mass of perception, neither as perceiving nor as not perceiving; as unseen; as beyond the reach of ordinary transaction; as ungraspable; as without distinguishing marks; as unthinkable; as indescribable; as one whose essence is the perception of itself alone; as the cessation of the visible world; as tranquil; as auspicious; as without a second. That is the self (atman), and is that which should be perceived.

Michael Comans disagrees with Nakamura's suggestion that "the concept of the fourth realm (caturtha) was perhaps influenced by the Sunyata of Mahayana Buddhism", stating that "[T]here can be no suggestion that the teaching about the underlying Self as contained in the Mandukya contains shows any trace of Buddhist thought, as this teaching can be traced to the pre-Buddhist Brhadaranyaka Upanishad."

According to Ellen Goldberg, this fourth quarter describes a state of meditation; the insight during meditation of Turiya is known as amātra, the 'immeasurable' or 'measureless' in the Mandukya Upanishad, being synonymous with samādhi in Yoga terminology.

AUM and four states of consciousness

In the Mandukya Upanishad, AUM symbolizes the four states of consciousness. The three parts in A-U-M corresponds to waking, dreaming, and sleep states. The fourth state, (turīya avasthā), corresponds to silence, just as the other three correspond to AUM. It is the substratum of the other three states. It is, states Nakamura, atyanta-shunyata (absolute emptiness). According to Sharma, Turiya is "the common ground of all these states. It manifests itself in these three states and yet in its own nature it transcends them all".