The great mahāvākya (great saying) of the Chāndogya Upaniṣad — tat tvam asi (“That thou art”) — is invoked here as the defining mark (lakṣaṇa) of the teaching. Everything is Brahman of the nature of jñāna (knowledge/awareness). To know this is not to acquire new information but to undergo an identity shift: the limited “I” dissolves into the limitless Brahman. The sage who knows this is always content (sadā tṛpta), always at peace (sadā santa).