This is in truth That.

Repetition of verse 15, confirming the essential identity. After Naciketas’s insistence, Yama (or the text itself) reaffirms the fundamental truth. The identification between etat (this — the immediate, the apparent) and tat (that — the absolute, Brahman) is the core of the teaching.

The repetition indicates that this truth is not a single concept but the basis of all subsequent understanding. Every time the mind gets lost in multiplicity, it must remember: etad vai tat — all this is in truth That, the sole reality without a second.

In the narrative context, this repetition marks the point where Yama finally yields to Naciketas’s demand. He has tried all possible distractions and now must face the truth. The verse acts as a turning point: the attempt at evasion ends and genuine revelation begins.

The formula etad vai tat becomes a mahāvākya (great statement) equivalent to “Tat tvam asi” (That you are) from the Chāndogya Upaniṣad. It affirms the non-duality (advaita) of the apparent and the real, of phenomenon and noumenon, of world and Brahman.