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.
A detailed manual of yoga: elements, breaths, channels, postures, the count of breaths, and the signs of approaching death. By the end it turns out that all this work on the body leads to the contemplation of Vāsudeva in the heart.