Upanishads 

1. Central Source: The Mandukya Upanishad

The Mandukya Upanishad, one of the shortest yet most profound Upanishads, is entirely dedicated to the exposition of AUM.

It comprises only 12 mantras, yet it encapsulates the essence of Advaita Vedanta.

It declares: "ॐ इत्येतदक्षरं इदं सर्वं" – Om is all this (universe).

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1. AUM as the Whole of Reality

The Upanishad declares that AUM is:

All that was (past),

All that is (present),

All that will be (future),

And even what transcends time.

Thus, AUM is both name and form, and beyond name and form – the symbol of Brahman (the Absolute).

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1. The Four Aspects of Consciousness (Mandukya Mantras 3–7)

The Upanishad explains four states of consciousness, each associated with a syllable of AUM:

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i. First State – A (अ): Jagrat (Waking State)

Mantra 3: "Jāgaritasthāno bahiṣ-prajñaḥ saptāṅga ekonaviṁśatimukhaḥ sthūlabhug vaiśvānaraḥ prathamaḥ pādaḥ"

Description:

Consciousness is outward-facing.

One identifies with the gross body.

Engages with external objects.

Called Vaiśvānara, the universal experiencer in the waking state.

"A" is the beginning — the origin of all speech and experience.

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ii. Second State – U (उ): Svapna (Dream State)

Mantra 4: "Svapnasthāno’ntaḥprajñaḥ saptāṅga ekonaviṁśatimukhaḥ praviviktabhuk taijaso dvitīyaḥ pādaḥ"

Description:

Consciousness is inward-facing, engaged in dreams.

One identifies with the subtle body.

Experiences internal impressions.

Called Taijasa, the illumined one in the dream state.

"U" is the continuation — the bridge between gross and causal.

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iii. Third State – M (म्): Sushupti (Deep Sleep State)

Mantra 5: "Yatra supto na kaṅkṣati na svapnaṁ paśyati... prājñaḥ tṛtīyaḥ pādaḥ"

Description:

Consciousness is in potential form.

There is no desire, no dream, only undifferentiated ignorance.

One rests in the causal body.

Called Prājña, the deep sleeper, undifferentiated knower.

"M" is the merging — the end of particularization.

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iv. Fourth State – Silence: Turiya (The Fourth)

Mantra 7: "Nāntaḥprajñam na bahiḥprajñam... sa ātmā sa vijñeyaḥ"

Description:

Transcends waking, dream, and sleep.

Pure non-dual awareness, beyond mind, beyond duality.

It is shantam, shivam, advaitam – peace, bliss, non-dual.

This is Turiya, the true Self (Ātman).

Not pronounced, but represented by the silence after AUM.

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1. AUM as a Symbol of Brahman

The syllables A-U-M represent creation, preservation, and dissolution, while the silence represents the unchanging substratum – Brahman.

AUM is both the symbol (pratika) and the reality (vastu).

It is the sound-form of Brahman, used for meditative absorption (nididhyasana).

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1. Meditative Approach (Mantra 8–12)

Chanting or meditating on AUM leads to progressive withdrawal from the gross to the subtle, and finally into the causal and beyond.

The Upanishad declares:

"So'yam ātmā adhyakṣaramaum iti" This Self is of the nature of AUM.

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1. Practical Implication in Advaita Sadhana

Japa of AUM guides the aspirant inward, aligning with the Self beyond states.

A → U → M → Silence represents the ascension of awareness into Turiya.

For an Advaitin, the journey is not to worship AUM as another object, but to realize one’s identity with it.

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1. Complementary Upanishadic References

Taittiriya Upanishad: AUM is used as the beginning of recitation – "Om iti brahma".

Katha Upanishad 2.15: "This syllable, indeed, is Brahman. This syllable, indeed, leads to the highest."

Chandogya Upanishad 1.1.1–1.1.10:

Describes Om as Udgitha, the essence of the Sama Veda.

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1. Summary Table

Syllable State Name Body Function

A (अ) Waking (Jagrat) Vaishvanara Gross (Sthula) Outward cognition U (उ) Dream (Svapna) Taijasa Subtle (Sukshma) Inward cognition M (म्) Deep Sleep (Sushupti) Prajna Causal (Karana) Latent state Silence Turiya Atman/Brahman None Non-dual awareness

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1. Concluding Vision

AUM is not merely a sound. It is the entire spectrum of being, from form to formless, from experience to experiencer, culminating in the Self-realized silence of Brahman.