Synopsis The present book exhaustively deals with the origin and development, system of the Upanishads. In brief it propagates the fundamentals of philosophy found in Upanishads. Upanishads are termed as Vedanta. They are the height of Indian culture and philosophy. The book highlights how there is a system in the philosophy of Upanishads. First, there developed the doctrine of Brahman and Atman giving rise to idealism. When the empirical knowledge asserted them it developed into cosmology or the doctrine of the universe. Idealism slowly gave way to Pantheism, Theism, Atheism and Deism. With the rise of Sankhya developed system psychology or the doctrine of soul. Side by side with them developed eschatology or the doctrine of transmigration and emancipation, manifested in two ways—Yoga and Samnyasa.