Adyar Library Series 90 - Upanisad
The different kinds of meditation mentioned in the principal Upanisad-s with special reference to Gayatri-vidya. Introduction by Dr. V. Raghavan, index
The Chandogya, Brhadaranyaka, Taittiriya and other Upanisa-s deal with large number of Vidya-s (secret doctrines) for Upasana (meditation) by which one an attain true knowledge of the self and liberation.
Thirty-two such vidya-s are collected and their significance are dealt.