Mandukya Upanishad, seventh verse:

Text

नान्तःप्रज्ञं न बहिःप्रज्ञं नोभयतःप्रज्ञं न प्रज्ञानघनं न प्रज्ञं नाप्रज्ञम् | अदृश्यमव्यवहार्यमग्राह्यमलक्षणमचिन्त्यमव्यपदेश्यमेकात्मप्रत्ययसारं प्रपञ्चोपशमं शान्तं शिवमद्वैतं चतुर्थं मन्यन्ते स आत्मा स विज्ञेयः || 7 ||

nāntaḥprajñaṃ na bahiḥprajñaṃ nobhayataḥprajñaṃ na prajñānaghanaṃ na prajñaṃ nāprajñam | adṛśyamavyavahāryamagrāhyamalakṣaṇamacintyamavyapadeśyamekātmapratyayasāraṃ prapañcopaśamaṃ śāntaṃ śivamadvaitaṃ caturthaṃ manyante sa ātmā sa vijñeyaḥ || 7 ||

7. Turīya is not that which is conscious of the internal (subjective) world, nor that which is conscious of the external (objective) world, nor that which is conscious of both, nor that which is a mass all sentiency, nor that which is simple consciousness, nor that which is insentient. (It is) unseen (by any sense organ), not related to anything, incomprehensible (by the mind), uninferable, unthinkable, indescribable, essentially of the nature of Consciousness constituting the Self alone, negation of all phenomena, the Peaceful, all Bliss and the Non-dual. This is what is known as the fourth (Turīya). This is the Ātman and it has to be realised.

      (‘Consciousness’ as the nearest English word is used.)

Shankara Bhashya (commentary)

(Objection)—The object was to describe Ātman as having four quarters. By the very descriptions of the three quarters, the fourth is established as being other than the three characterised by the “conscious of the subjective”, etc. Therefore the negation (of attributes relating to the three quarters) for the purpose of indicating Turīya implied in the statement, “Turīya is that which is not conscious of the subjective”, etc., is futile. (Reply)—No. As the nature of the rope is1 realised by the negation of the (illusory) appearances of the snake, etc., so also it is intended to establish the very Self, which subsists in the three states, as Turīya. This2 is done in the same way as (the great Vedic statement) “Thou art that”. If Turīya were, in fact, anything different3 from Ātman subsisting in the three states, then, the teachings of the Scriptures would have no meaning on4 account of the absence of any instrument of knowledge (regarding Turīya). Or the other (inevitable alternative would be to declare absolute nihilism ( śūnya) to be the ultimate Truth. Like the (same) rope mistaken as snake, garland, etc., when the same Ātman is mistaken as Antaḥprajña (conscious of the subjective) etc., in the three states associated with different characteristics, the knowledge, resulting from the negation of such attributes as the conscious of the subjective, etc., is the means of establishing the absolute absence of the unreal phenomena of the world (imagined) in Ātman. As a matter of fact, the two5 results, namely, the negation of (superimposed) attributes and the disappearance of the unreal phenomena happen at the same time. Therefore no additional6 instrument of knowledge or no other7 effort is to be made or sought after for the realisation of Turīya. With the cessation of the idea of the snake, etc., in the rope, the real nature of the rope becomes revealed and this happens simultaneously with the knowledge of the distinction between the rope and the snake. But those who say that the knowledge, in addition to the removal of the darkness (that envelopes the jar), enables8 one to know the jar, may as well affirm9 that the act of cutting (a tree), in addition to its undoing the relation of the members of the body intended to be cut, also functions (in other ways) in other parts of the body. As the act of cutting intended to divide the tree into two is said to be complete with the severance of the parts (of the tree) so also the knowledge employed to perceive the jar covered by the darkness (that envelopes it) attains its purpose when it results in removing the darkness, though that is not the object intended to be produced. In such case the knowledge of the jar, which is invariably10 connected with the removal of the darkness, is not the result accomplished by the instrument of knowledge. Likewise, the knowledge, which is (here) the same as that which results from the negation of predicates, directed towards the discrimination of such attributes as “the conscious of the subjective” etc., superimposed upon Ātman, cannot11 function with regard to Turīya in addition to its act of negating of such attributes as “the conscious of the subjective” which is not the object intended to be produced. For, with the negation of the attributes such as “conscious of the subjective,” etc., is12 accomplished simultaneously the cessation of the distinction between the knower, the known and the knowledge. Thus it will be said later on, “Duality cannot exist when Gnosis, the highest Truth (non-duality), is realised.” The knowledge of duality cannot exist even for a moment immediately after the moment of the cessation of duality. If it should remain, there would13; follow what is known as regressus ad infinitum; and consequently duality will never cease. Therefore it is established that the cessation of such unreal attributes as “conscious of the subjective” etc., superimposed upon Ātman is14 simultaneous with the manifestation of the Knowledge which, in itself, is the means (pramāṇa) for the negation of duality. By the statement that it (Turīya) is “not conscious of the subjective” is indicated that it is not “Taijasa”. Similarly by the statement that it is “not conscious of the objective,” it is denied that it (Turīya) is Viśva. By saying that it is “not conscious of either”, it is denied that Turīya is any intermediate state between15 the waking and the dream states. By the statement that Turīya is “not a mass all sentiency”, it is denied that it is the condition of deep sleep—which is held to be a causal16 condition on account of one’s inability to distinguish the truth from error (in deep sleep). By saying that it is “not simple consciousness”, it is implied that Turīya cannot17 simultaneously cognize the entire world of consciousness (by a single act of consciousness). And lastly by the statement that it is “not unconsciousness” it is implied that Turīya is not insentient or of the nature of matter. (Objection)—How,18 again, do such attributes as “conscious of the subjective,” etc., which are (directly) perceived to subsist in Ātman become non-existent only by an act of negation as the snake, etc. (perceived) in the rope, etc., become non-existent (by means of an act of negation)? (Reply)—Though19 the states (waking and dream) are really of the essence of consciousness itself, and as such are non-different from each other (from the point of view of the substratum), yet one state is seen to change20 into another as do the appearances of the snake, water-line, etc., having for their substratum the rope, etc. But the consciousness itself is real because it never changes. (Objection)—Consciousness is seen to change (disappear) in deep sleep. (Reply)—No, the state of deep sleep is a matter of experience.21 For the Śruti says, “Knowledge of the Knower is never absent.” Hence it (Turīya) is “unseen”22; and because it is unseen therefore it is “incomprehensible”.23 Turīya cannot be apprehended by the organs of action. Alakṣanam means “uninferable”,24 because there is no Liṅga (common characteristic) for its inference. Therefore Turīya is “unthinkable”25 and hence “indescribable”26 (by words). It is “essentially27 of the nature of consciousness consisting of Self”. Turīya should be known by spotting that consciousness that never changes in the three states, viz., waking, etc., and whose nature is that of a Unitary Self. Or,28 the phrase may signify that the knowledge of the one Ātman alone is the means for realising Turīya, and therefore Turīya is the essence of this consciousness or Self or Ātman. The Śruti also says, “It should be meditated upon as Ātman.” Several attributes, such as the “conscious of the subjective” etc., associated with the manifestation (such as, Viśva, etc.) in each of the states have already been negated. Now by describing Turīya as “the cessation of illusion”, the attributes which characterise the-three states, viz., waking, etc., are negated. Hence it is “ever29 Peaceful”, i.e., without any manifestation of change—and “all30 bliss”. As it is non-dual, i.e., devoid of illusory ideas of distinction, therefore it is called “Turīya”, the “Fourth”,31 because it is totally distinct (in character) from the three quarters which’ are mere appearances. “This, indeed, is the Ātman and it should be known,” is intended to show that the meaning of the Vedic statement, “That thou art”, points to the relationless Ātman (Turīya) which is like the rope (in the illustration) different from the snake, line on the ground, stick, etc,, which are mere appearances. That Ātman which has been described in such Śruti passages as “unseen, but the seer”, “the consciousness of the seer is never absent”, etc., should be known. (The incomprehensible) Turīya “should be known”, and this32 is said so only from the standpoint of the previously unknown condition, for duality cannot exist when the Highest Truth is known.