Sankara, the eight-century Indian philosopher, is generally regarded as the greatest thinker in the long history of Indian philosophy as well as in the metaphysical tradition known as Vedanta. Advaita Vedanta, the schoolor system founded by him, stresses the Advaita or non-dualist approach to the problem of existence and ultimate reality, and has been the main current of thought in India for hundreds of years. Most of Sankara's works are commentaries on other classics of Indian thought, like Upanishds, the Bhagavadgita, and the Brahmasutra. The Upadesasahasri, or "A Thousand teaching," here critically edited and translated into English, is however, the only independent and non commentary work that can safely be attributed to him; the other independent writings traditionally ascribed to him are all probably spurious.