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.
An inventory of the person: what the body is made of, how many parts it has, what powers are in it, and who is their master. A book without argument, but precise — one of those that supply a vocabulary for everything else.