Introduction:

The Mandukya Upanishad, belongs to Atharva Veda. It is the shortest of all the Upanishads with 12 verses and placed in the 6th position in the list of Ten Principal Upanishads. This Upanishad teaches the significance of the sacred syllable ॐ~AUM (OM) and it correlates with four states of Consciousness. It describes the Turiya state, the state of transcendental Consciousness in which all the divisions and Duality disappears. The SELF alone exists in its pure state. Upon meditating on the Mystic Syllable , OM , mind can be trained to achieve freedom gradually to attain ultimate Reality.

माण्डूक्योपनिषत्

॥ अथ माण्डूक्योपनिषत् ॥

ॐ भद्रं कर्णेभिः श‍ृणुयाम देवा
भद्रं पश्येमाक्षभिर्यजत्राः ।
स्थिरैरङ्गैस्तुष्तुवाꣳसस्तनूभिर्व्यशेम देवहितं यदायुः ॥

स्वस्ति न इन्द्रो वृद्धश्रवाः
      स्वस्ति नः पूषा विश्ववेदाः ।
स्वस्ति नस्तार्क्ष्यो अरिष्टनेमिः
      स्वस्ति नो बृहस्पतिर्दधातु ॥

ॐ शान्तिः शान्तिः शान्तिः ॥

Om! Shining Ones! May our ears hear the good. May our eyes see the good. May we serve HIM with the whole strength of our body. May we, all our life, carry out HIS will. Peace, peace and peace be everywhere.

Everything is OM

 ॐ इत्येतदक्षरमिदꣳ सर्वं तस्योपव्याख्यानं
भूतं भवद् भविष्यदिति सर्वमोङ्कार एव
यच्चान्यत् त्रिकालातीतं तदप्योङ्कार एव  ॥ १॥

First Mantra: Hari OM! OM ityetadakSharamidaM sarvam tasyopavyAkhyAnaM bhutaM bhavadH bhaviShyaditi sarvamoMkAra eva. yachchaanyatH trikAlAtitaM tadapyoMkaAra eva.(1) 

OM + ity + etad + akSharam => means This syllable is OM.                idaM sarvam => means This (OM) is all. tasya + upavyAkhyAnaM =>  Explanation begins with this Omkar.  bhutaM ( past) bhavadH ( present) bhaviShyat (future)  sarvam oMkAra eva. => Past , present future; everything is OM. yachchaanyatH trikAlA (three time periods) titaM tadapy + oMkaAra eva. ( even that too is OM which transcends three division of time).

Mantra 1. Hari OM! The Word OM is Imperishable. All this it’s manifestation. Past , present future; everything is OM. Whatever transcends the three divisions of time , that too is OM.

सर्वं ह्येतद् ब्रह्मायमात्मा ब्रह्म सोऽयमात्मा चतुष्पात् ॥ २॥

Second Mantra: 
 sarvaM hyetad brahmAyamAtmA brahma so ayamAtma chatuShpAt (2) 

Mantra 2: All this is verily Brahman. (ब्रह्मायमात्मा ब्रह्म) ” Ayam atma Brahma” There is nothing that is not Brahman. The Personal Self is the impersonal Brahman. (सोऽयमात्मा चतुष्पात् ) It has four aspects (states), also known as four quarters.

” Ayam atma Brahma” is one of the four mahaVakyas from four Vedas. It signifies the realization that who I am really is that same Brahman. The word “chatuShpad” (चतुष्पात् )refers to the four aspects of Consciousness. Three states of Consciousness: 1) Waking[GROSS], 2) Dreaming [SUBTLE] and 3) Deep Sleep [CAUSAL]. Fourth is the Reality which is the Background of all states. Details to be known from the following verses.

The first pada: Waking state Consciousness.

जागरितस्थानो बहिष्प्रज्ञः सप्ताङ्ग एकोनविंशतिमुखः
स्थूलभुग्वैश्वानरः प्रथमः पादः ॥ ३॥

Third Mantra : jAgaritasthAno bahiShpraj~naH saptA~Nga ekonaviMshatimukhaH sthUlabhugvaishvAnaraH prathamaH pAdaH (3)

Mantra 3: First comes the material condition-common to all. Perception turned outward. Seven limbs*( सप्ताङ्ग = 7 limbs), Nineteen mouths**( एकोनविंशतिमुखः = 19 mouths), wherein the Self enjoys course matter. This is known as waking condition. Waking State~ jAgrat.  The individual is known here as vaishvAnara (Virat) who is in the waking state of consciousness(the gross world). Bahih PrajNa: (बहिष्प्रज्ञः) means the outward tendencies which is predominant in this state. The Seven Limbs: the macrocosm and microcosm are paired up and through 19 mouths, one enjoys the gross objects( स्थूलभुग्वैश्वानरः ) of this world.

*Seven limbs are: Heavens(he ad), Sun(eye) air(breath), fire(heart), water(belly), earth(feet) and space(body).

**Nineteen mouths are: 1) Five organs of senses- Hearing, Touching, Seeing, Tasting and Smelling. 2) Five organs of action- Speaking, Handling, Walking, Generating and Excreting. 3) Five living fires- Prana, Apana, Samana,Vayana, and Udana. 4) Four states of mind:  Discursive mind (Manas), Discriminative mind(Buddhi), Mind-Material(Chitta) and Personality(Ahangkara).  { 3×5+4 = 19}

The Second Pada – Dream state Consciousness.

स्वप्नस्थानोऽन्तःप्रज्ञः सप्ताङ्ग एकोनविंशतिमुखः
प्रविविक्तभुक्तैजसो द्वितीयः पादः ॥ ४॥

Fourth Mantra: svapnasthAno.antaHpraj~naH saptA~Nga
ekonaviMshatiMukhaHpraviviktabhuk taijaso dvitIyaH pAdaH (4)

Mantra 4: Dream State:  Taijasa~  the dreamer creates dream world out of his or her own mind. In the dream state, entire dream world seems to be as real as is experienced in waking condition, whatever be the time duration of the dream.
In dream, the person experience the subtle world  (pain or pleasure,  joy or fear) through dream sense organs, not the physical sense organs. In dream, mind reflects the impression left by waking state like a piece of canvas with the pictures painted on it. Dream state experience that as if it were like waking. Like in waking state, here the sphere of activity is inward. It enjoys the subtle objects (प्रविविक्तभुक्तैजसो ) of the mental world. Seven limbs and nineteen mouths also work here but INWARD. Here Anta prajNa is predominant. 

According to BRRihadAraNyaka Upanishad IV.3,9:
When he dreams, he takes away a little of the impression of this all embracing world (the waking state), himself puts the body aside and himself creates a dream body in it’s place, revealing his own lustre by his own light and dreams. In this state, the man himself becomes the light.

The Third Pada -Deep Sleep Consciousness      (Vyashti)

यत्र सुप्तो न कञ्चन कामं कामयते न कञ्चन स्वप्नं
पश्यति तत् सुषुप्तम् । सुषुप्तस्थान एकीभूतः प्रज्ञानघन
एवानन्दमयो ह्यानन्दभुक् चेतोमुखः प्राज्ञस्तृतीयः पादः ॥ ५॥

Fifth Mantra: yatro supto na ka~nchana kAmaM kAmayate na ka~nchana svapnaMpashyati tat suShuptam. suSuptasthAna ekibhUtaH praj~nAnaghana evAnandamayo hyAnandabhukchetomukhaH prAj~nastRRitIyaH pAdaH. (5)

Mantra 5:The Deep Sleep state (SuShupta~SU=Sundar/excellent +sUpta=Sleep) ~ prajNa and antaryAmin.
In this state, waking world and dreaming world temporarily ceases. We exist here in non dual state. Most refreshing state. A state of Bliss(with ignorance). In the waking and dreaming state, we are diverted from this state of bliss, though knowledge of our true nature is absent here. All the perceived limitations are removed in this temporary state but ready to spring forth as soon as we move to waking world.

In that sleep state, not for anything desirable does one have any desire.(यत्र सुप्तो न कञ्चन कामं कामयते).  Not the slightest trace of dream does it see in that state of deep sleep.(न कञ्चन स्वप्नं पश्यति तत् सुषुप्तम् ). In the sphere of deep sleep, there is just one ” homogenous mass of consciousness” alone (सुषुप्तस्थान एकीभूतः प्रज्ञानघन).  Because of his union with the Self and his unbroken knowledge of it, he is filled with joy, he knows his joy, his mind is illuminated (एवानन्दमयो ह्यानन्दभुक् चेतोमुखः). Such is the called third quarter called prajNa (चेतोमुखः प्राज्ञस्तृतीयः पादः).

The Ishwara State of Consciousness.

एष सर्वेश्वरः एष सर्वज्ञ एषोऽन्तर्याम्येष योनिः सर्वस्य
प्रभवाप्ययौ हि भूतानाम् ॥ ६॥

Sixth Mantra: eSha sarveshvaraH eSha sarvaj~na eSho.antaryAmyeSha yoniH sarvasyaprabhavApyau hi bhUtAnAm. (6)

Mantra 6: The Self is Lord of all. He is inner controller and inhabitant of the hearts of all. He is Omniscient, the source of all; creator and dissolver of  all beings. there is nothing He does not know.

The fruit of the process of “Negation”:

नान्तःप्रज्ञं न बहिष्प्रज्ञं नोभयतःप्रज्ञं न प्रज्ञानघनं
न प्रज्ञं नाप्रज्ञम् । अदृष्टमव्यवहार्यमग्राह्यमलक्षणं
अचिन्त्यमव्यपदेश्यमेकात्मप्रत्ययसारं प्रपञ्चोपशमं
शान्तं शिवमद्वैतं चतुर्थं मन्यन्ते स आत्मा स विज्ञेयः ॥  ७॥

Seventh Mantra: nAntaHpraj~naM na bahiShpraj~naM  nobhayataHpraj~nam  napraj~nAnaghanaM  na praj~nam nApraj~nam.
adRRiShTamavyavahAryamagrAhyamalakShaNamachintyamavyap adeshyamekAtmapratyayasAraM manyante sa AtmA sa vij~neyaH.(7)

Mantra 7: Negation Phase: He is not knowable by perception, turned inward or outward, nor by both combined. He is neither that which is known, nor that which is not known, nor is He the sum of all that might be known. He can not be seen, grasped, bargained with. He is undefinable, unthinkable, indescribable.

nAntaHpraj~naM = not the knower of the internal (subtle)

na bahiShpraj~naM = not the knower of the external (gross)

na bahiShpraj~naM = not the knower of both

napraj~nAnaghanaM = not the knower of deep sleep

na praj~nam = nor consciousness

nApraj~naM = nor unconsciousness.

Assertion Phase: The only proof of His existence is union with Him. The world disappears in Him. He is the peaceful, the good, the ONE without a second. This is the fourth condition of the Self- The most worthy of all. This is the Atman. 

This 7th mantra is most important among the Vedic scriptures. This mantra describes the nature of Absolute reality~ Brahman. 

Conclusion:

According to the Mandukya Upanishad, four conditions of  The Self (“Atman”) can be described as below :-
1) Waking condition: Perception turned outward.
2) Mental condition : Perception turned inward, known as dreaming condition. Self enjoys subtle
matter.
3)Deep sleep condition: No desire, no dream. This is intellectual condition. Because of union with Self
and his unbroken knowledge, one feels joy. He knows joy. His mind is illuminated.
ॐ~AUM
A~ Waking
U~ Dreaming
M~ Deep Sleep
The Fourth condition of the Self  can be achieved through deep meditation that corresponds to “OM” as ONE. Self is Whole and beyond bargain. The world disappears in HIM. SELF is one without a second. This condition is known as #Turiya#

Recommended readings:

1. Back to the Truth: 5000 years of ADVAITA by Dennis Waite.**
2. THE TEN PRINCIPAL UPANISHADS: Translated by Shree Purohit** Swami and W.B.Yeats
3. Brahma Sutra Bhasya of Sankaracharya: Translated by Swami Gambhirananda.**
4. Commentary of Mandukya Upanishad: By Swami Krishnananda.
5. MANDUKYA Upanishad By Swami GuruBhaktananda.
6. EIGHT UPANISADS -VOL-1 with commentary of Sankaracharya, Translated by SWAMI GAMBHIRANANDA.
7. THE TAITTIRIYA UPANISHAD: SHIKSHAVALLI-ANANDAVALLI-BHRIGUVALLI with Sri Shankara’s Commentary By Sri Swami Satchidanandera Saraswati.
8. A-U-M Awakening to Reality : By Dennis Waite***
9. Information available on internet.

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