In plain EnglishThis Ātman, as related to the syllable Oṃ, quarter by quarter — the quarters of Ātman are the measures (A, U, M) of Oṃ, and the measures are the quarters.
Layer 2 — What it means
The Upaniṣad now performs its most elegant move: it shows that the syllable Oṃ and the four states of consciousness are the same structure, described from two different angles.
The syllable Oṃ has three sounds and a silence: A (the open vowel), U (the middle), M (the closing consonant), and the resonance that remains after M fades. These four correspond exactly to the four states: waking, dream, deep sleep, and Turīya. The syllable is a sonic map of consciousness — and consciousness is the experiential reality of what the syllable points at.
This is why verse 1 could say everything is Oṃ. It was not a religious claim. It was a structural one. The syllable and the full range of conscious experience have the same architecture.
Layer 3 — What it points to
Reading this page will give you the concept clearly. But the Upanishads were not written to be understood the way you understand chemistry or history. They were written to point toward something you can only recognise in yourself. That recognition is not on this page. This page only clears the way.
In plain EnglishThis Ātman, as related to the syllable Oṃ, quarter by quarter — the quarters of Ātman are the measures (A, U, M) of Oṃ, and the measures are the quarters.
Layer 2 — What it means
The parallel is formally stated: mātrayā pādāḥ — the quarters (of Ātman) are the measures (of Oṃ); pādā mātrāḥ — the measures are the quarters. The identification is mutual and complete. Verses 9–11 will work out each correspondence in turn. Verse 12 will identify the silence after M — the fourth measure, which has no phoneme — with Turīya.
Śaṅkara's point in his commentary on this verse: the practitioner of upāsanā (meditative contemplation) can use the syllable Oṃ as a support for inquiry into the four states — not because Oṃ causes Turīya, but because the contemplation of the syllable's structure mirrors the inquiry into consciousness's structure. The map and the territory are, in this case, made of the same material.
Layer 3 — What it points to
Reading this page will give you the concept clearly. But the Upanishads were not written to be understood the way you understand chemistry or history. They were written to point toward something you can only recognise in yourself. That recognition is not on this page. This page only clears the way.
In plain EnglishThis Ātman, as related to the syllable Oṃ, quarter by quarter — the quarters of Ātman are the measures (A, U, M) of Oṃ, and the measures are the quarters.
Layer 2 — What it means
This verse establishes the hermeneutic key for reading verses 9–12. The correspondences are not arbitrary mnemonic devices. They arise from the structural identity between the phonological structure of Oṃ and the phenomenological structure of consciousness as the Upaniṣad analyses it. Gauḍapāda (Kārikā I.8) treats this as an upāya — a skilful means — rather than an ontological claim: the syllable is used as a contemplative support precisely because it has the same fourfold structure. The contemplation of Oṃ moving from A through U through M to silence enacts, in miniature, the movement of inquiry from waking through dream through deep sleep to Turīya.
Layer 3 — What it points to
Reading this page will give you the concept clearly. But the Upanishads were not written to be understood the way you understand chemistry or history. They were written to point toward something you can only recognise in yourself. That recognition is not on this page. This page only clears the way.