The Taittirīya Upanishad is embedded as three chapters (adhyāya) of the Yajurveda. The Taittirīya Upanishad is associated with the Taittirīya school of the Yajurveda, attributed to the pupils of sage Tittiri (literally, "Partridge"). The Upanishad includes verses that are partly prayers and benedictions, partly instruction on phonetics and praxis, partly advice on ethics and morals given to graduating students from ancient Vedic gurukula-s (schools), partly a treatise on allegory, and partly philosophical instruction. Taittiriya is a Sanskrit word that means "from Tittiri". The root of this name has been interpreted in two ways: "from Vedic sage Tittiri", who was the student of Yāska; or alternatively, it being a collection of verses from mythical students who became "partridges" (birds) in order to gain knowledge. Each chapter of the Taittiriya Upanishad is called a Valli (वल्ली), which literally means a medicinal vine-like climbing plant that grows independently yet is attached to a main tree.