The Upani@sads are also known by another name Vedanta, as they are believed to be the last portions of the Vedas (_veda-anta_, end); it is by this name that the philosophy of the Upani@sads, the Vedanta philosophy, is so familiar to us. A modern student knows that in language the Upani@sads approach the classical Sanskrit; the ideas preached also show that they are the culmination of the intellectual achievement of a great epoch. As they thus formed the concluding parts of the Vedas they retained their Vedic names which they took from the name of the different schools or branches (_s'akha_) among which the Vedas were studied [Footnote ref 42]. Thus the Upani@sads attached to the Brahma@nas of the Aitareya and Kau@sitaki schools are called respectively Aitareya and Kau@sitaki Upani@sads. Those of the Ta@n@dins and Talavakaras of the Sama-veda are called the Chandogya and Talavakara (or Kena) Upani@sads. Those of the Taittiriya school of the Yajurvedaform the Taittiriya and Mahanaraya@na, of the Ka@tha school the Ka@thaka, of the Maitraya@ni school the Maitraya@ni. The B@rhadara@nyaka Upani@sad forms part of the S'atapatha Brahma@na of the Vajasaneyi schools. The Is'a Upani@sad also belongs to the latter school. But the school to which the S'vetas'vatara belongs cannot be traced, and has probably been lost. The presumption with regard to these Upani@sads is that they represent the enlightened views of the particular schools among which they flourished, and under whose names they passed. A large number of Upani@sads of a comparatively later age were attached to the Atharva-Veda, most of which were named not according to the Vedic schools but according to the subject-matter with which they dealt [Footnote ref 43].
It may not be out of place here to mention that from the frequent episodes in the Upani@sads in which the Brahmins are described as having gone to the K@sattriyas for the highest knowledge of philosophy, as well as from the disparateness of the Upani@sad teachings from that of the general doctrines of the Brahma@nas and from the allusions to the existence of philosophical speculations amongst the people in Pali works, it may be inferred that among the K@sattriyas in general there existed earnest philosophic enquiries which must be regarded as having exerted an important influence in the formation of the Upani@sad doctrines. There is thus some probability in the supposition that though the Upani@sads are found directly incorporated with the Brahma@nas it was not the production of the growth of Brahmanic dogmas alone, but that non-Brahmanic thought as well must have either set the Upani@sad doctrines afoot, or have rendered fruitful assistance to their formulation and cultivation, though they achieved their culmination in the hands of the Brahmins.