Originally published in 1969, this book gives the text of the Readership Lectures which the author delivered at the University of Patna. He sets out the various strands of idealistic thought in India which stemmed from the Upanishads (c. 700 BC) and later from Buddhism, explaining in what sense these theories can be called 'idealism', bringing out the significant contributions of each of the principal Upanishads and comparing Buddhist idealism with that of Sankara (AD 800) and some of his followers.