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.
Instruction on renunciation: what is left behind, what words are said, what is taken along, and how one lives afterward. The rite is described step by step — one of the books by which renunciation was actually performed.