The Taittiriya Upanishad is one of the older, "primary" Upanishads commented upon by Shankara. It is associated with the Taittiriya school of the Black Yajurveda. It figures as number 7 in the Muktika canon of 108 Upanishads. It belongs to the Taittiriya recension of the Black Yajurveda and is constituted by the eighth and ninth chapters of Taittiriya Aranyaka. The tenth chapter of the same Aranyaka is the Mahanarayana Upanishad. The Taittiriya Upanishad describes the various degrees of happiness enjoyed by the different beings in creation.