Upanishad (Sans.) Lit., "Esoteric Doctrine." The third Division of the Vedas, and classed with revelations (sruti or "revealed word"). Some 150 of the Upanishads still remain extant, though no more than about twenty can be fully relied upon as free from falsification. These are all earlier than the sixth century bc. Like the Cabala, which interprets the esoteric sense of the Bible, so the Upanishads explain the mystic sense of the Vedas. Professor Cowell has two statements regarding the Upanishads as interesting as they are correct. Thus he says:

These works have (1) … one remarkable peculiarity, the total absence of any Brahmanical exclusiveness in their doctrine … They breathe an entirely different spirit, a freedom of thought unknown in any earlier work except the Rig-Veda hymns themselves; and (2) the great teachers of the higher knowledge (Gupta-Vidya ), and Brahmins, are continually represented as going to Kshatriya Kings to become their pupils (Chelas).

This shows conclusively that (a) the Upanishads were written before the enforcement of caste and Brahmanical power, and are thus only second in antiquity to the Vedas; and (b) that the occult sciences or the "higher knowledge," as Cowell puts it, is far older than the Brahmins in India, or even of them as a caste. The Upanishads are, however, far later than Gupta-Vidya , or the "Secret Science" which is as old as human philosophical thought itself.

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