The great forest of teaching: Yajnavalkya silences a hall of sages, then tells his wife why he truly loves her.
Dialogues in this Upanishad
Not for the Sake of the Husband — Leaving for the forest, Yajnavalkya offers Maitreyi half his wealth. She asks: will it make me immortal? No. Then teach me that instead.
Gargi and the Warning — In a hall of sages, Gargi presses Yajnavalkya — on what is the world woven, and that, and that? — until he warns her head will fall off.
I Am Brahman — Aham brahmasmi. The Upanishad's boldest line: whoever truly knows 'I am Brahman' becomes the All — and not even the gods can stop it.