 Hindu philosophical schools develop their philosophical position as an attempt to interpret and defend the various metaphysical theses that are found in the Vedas (the foundational Hindu scriptures) and more specifically the Upaniṣads. The Upaniṣads, literally “the last chapters, parts of the Veda”, are often thought of as expressing the crux or the purpose of the Veda. The concept of ātman (soul, self) as the essence of individual persons and knowledge of that ātman is the central focus in all of the Upanishads. The self (ātman) is primarily conceived of in the Upaniṣads as a pure subject of experiences, detached from the objects of its consciousness, enduring and changeless and separate and independent of its mental and physical states. In the Bṛhadāraṇyaka Upaniṣad, the sage Yājñavalkya says