The Upanishads, religious and philosophical texts of ancient India record the speculations of seers and sages about the ultimate meaning of life and the path to liberation. Rooted in older traditions, still they test bold new ideas about the world, the self and the highest truth. These lectures examine major thematic and stylistic issues in key Upanishads, with reference to their interpretation by great Hindu thinkers, and their relevance as well for comparative and Christian theologies.