The South Indian philosopher who gave Advaita Vedanta its classical form and Hinduism one of its most influential metaphysical systems, arguing that only one reality, Brahman, truly exists, that the individual self is identical with it, and that the world of separate things is appearance. His commentaries on the Upanishads, the Bhagavad Gita, and the Brahma Sutras made Advaita Vedanta one of the most influential intellectual articulations of the tradition.
Adi Shankara taught that, in the end, only one thing truly exists. Not many gods, not many souls, not even the solid world of separate objects, but a single, formless reality he called Brahman. The self you take to be private and your own is, at the deepest level, identical with it. Everything else, the whole crowded world of difference, is a kind of misperception, like mistaking a coiled rope for a snake in dim light. Liberation, on this view, is not produced like a new reward. It is realized as knowledge — waking to a unity that was always the case.