The previous verse said everything is Oṃ. This verse says everything is Brahman. These are the same statement — two ways of pointing at the single reality that underlies all appearances.
Then comes the turn that makes this Upaniṣad unlike any other: Ayam ātmā Brahma — this Ātman is Brahman. Not: Brahman is something vast and you are a small part of it. The deepest self — Ātman — is that entire reality. The wave and the ocean are the same substance.
The verse then says: this Ātman has four quarters. The rest of the Upaniṣad is the unfolding of those four — waking, dream, deep sleep, and Turīya. Everything that follows is an investigation of what you already are.
Layer 3 — What it points toThis verse contains what the Advaita tradition identifies as one of the four Mahāvākyas — great sayings: Ayam Ātmā Brahma — this self is Brahman. It appears here as a statement within the Upaniṣad's argument, not as a separate aphorism. Its force depends on the word ayam — this, here, immediate. Not a distant Brahman or an abstract one. The self you are right now.
The four quarters (catuṣpāt) signal the analytical method the text will use. The Upaniṣad proceeds by examining consciousness in its four modes — not to accumulate knowledge about Ātman but to exhaust every mode in which Ātman is not recognised as Brahman, until what remains is the recognition itself.
Śaṅkara's commentary notes that sarvam hi etad brahma refers to the entire manifest world as having Brahman as its ground — the kāraṇa (cause) present in and as its effects. The individual Ātman is not one of many Brahmans. It is Brahman appearing as if individual through the limiting adjunct (upādhi) of the body-mind.
Layer 3 — What it points toVerse 2 is the structural axis of the entire Upaniṣad. What follows (verses 3–12) is the analytic unpacking of catuṣpāt — four quarters. Gauḍapāda (Kārikā I.2) reads this verse as establishing that the investigation of the states of consciousness and the investigation of Brahman-Ātman identity are the same investigation. The phenomenology of consciousness (waking/dream/sleep/Turīya) is not preliminary to the metaphysics — it is the metaphysics, conducted through self-inquiry rather than inference about external objects.
The term pāda (quarter, foot) carries the further sense of foundation or support. The four pādas are not merely sections but modes in which Brahman-Ātman supports itself — the same reality seen from four angles of inquiry, converging on the recognition that Turīya (verse 7) is the unchanging witness present through all three conditional states.
Layer 3 — What it points to