(“session”), any of the speculative texts that contain elaborations in prose and verse of the Vedas, the most ancient Hindu sacred literature.

The name Upanishad implies sitting at the feet of the teacher, and the Upanishads, of which approximately 108 are known, record the views of a succession of Hindu teachers and sages who were active as early as 1000 BC and who flourished about 600 BC. The texts form the basis of much of later Indian philosophy. They represent the final stage in the tradition of the Vedas, so the teaching based on them is known as the Vedānta (Sanskrit: “Conclusion of the Veda”). The older Upanishads may be part of the Brāhmaṇas (commentaries) of their respective Vedas but are distinguished from them both by increased philosophical and mystical questioning and by their diminished concern with Vedic deities and sacrificial rites.

The special philosophical concern of the Upanishads is with the nature of reality. There is a development toward the concept of a single supreme being, and knowledge is directed toward reunion with it. Of fundamental importance to all Hindu thought is the equation in some of the Upanishads of atman (the self) with Brahman (ultimate reality). The nature of morality and of eternal life is discussed, as are such themes as the transmigration of souls and causality in creation.

The appearance in Europe in the early 19th century of second- and third-hand translations of the Upanishads had a profound effect on certain thinkers, notably in Germany; the philosopher Arthur Schopenhauer fully acknowledged their influence on his thought.