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 story of the boy Naciketas, given by his father to Death and waiting three days at Yama's gate. Death gives him three boons and teaches: the body is a chariot, the intellect the driver, the senses the horses; the path is narrow as a razor's edge; and He is disclosed not by reasoning, but to whomever He Himself chooses.