The Upanishads represent for the Hindu approximately what the New Testament represents for the Christian. The earliest of these spiritual treatises, which vary greatly in length, were put down in Sanskrit between 800 and 400 BC. This selection from twelve Upanishads, with its illuminating introduction by Juan Mascar5, whose translation of the Bhagavad Gita is also in the Penguin Classics, reveals the paradoxical variety and unity, the great questions and simple answers, the spiritual wisdom and romantic imagination of these 'Himalayas of the Soul'.