The Upaniṣads — the philosophical core of the Vedic tradition, revealing the nature of Brahman, the Ātman, knowledge, action and liberation. The ten principal Upaniṣads together with select minor Vaiṣṇava Upaniṣads.
"The Adamantine Needle" — eleven lines examining who a brahmin is. Body, lineage, birth, learning, and rite are rejected one by one; what remains is a single mark — the vision of the non-dual — and it cannot be inherited.