They are doctrinal expositions found mostly in the final parts of the Brahmanas and Aranyakas of the four vedas. Large number of Upanishads are available even today, with commentaries on them by representatives of various schools of Vedanta. Every text is connected to the veda in which it is found, and the teachings from Upanishad are often presented in the context of a particular vedic hymn or ritual. Vedanta traditions often refer to upanishads as the Sruti Prasthana, or the revealed scripture, from which knowledge of brahman is obtained.