The Summit — Upaniṣads
The Veda has two wings: the karma-kāṇḍa (mantra, brāhmaṇa, āraṇyaka) which enjoins action, and the jñāna-kāṇḍa — the Upaniṣads — which knows. The second completes the first. Here, at the summit of the source, the landscape finally names its center.
The mahāvākya is not a definition. It is an identification — the report of a seer who has seen, stated with grammar strong enough to hold. Being (satya), awareness (jñāna), infinitude (ananta): not three things that Brahman has, but what Brahman is.
The center is a school's reading
This naming belongs to Vedānta. Mīmāṃsā stops at dharma; Nyāya at pramāṇa; Sāṅkhya at puruṣa and prakṛti. To put this mahāvākya at the root of the landscape would be to make one school’s center into the framework of all. We place it where it belongs: at the summit, not the gate.
The great sentences
Each school of Vedānta leans on a mahāvākya — a “great sentence” whose hearing is meant to be an event, not information.
These are not propositions to agree with. They are instructions for seeing. The method that delivers them is the same one the whole landscape runs on — hearing, reflecting, realizing — and it is where we turn next.