Commentary on the Brahma Sūtras (Brahmasūtrabhāṣya)

Shankara's commentary on the Brahma Sūtras, the terse aphorisms attributed to Bādarāyaṇa that systematise the teaching of the Upaniṣads, is the central text of Advaita (non-dual) Vedānta. It opens with a famous preamble on superimposition (adhyāsa): we mistakenly lay the features of body and mind onto the self, as one might take mother-of-pearl for silver. The first book argues that the Upaniṣads all point to one Brahman, pure consciousness, as the cause of the world and identical with the inner self (ātman). The second answers objections and refutes rival schools, including Sāṃkhya, Vaiśeṣika atomism, the Buddhists and the Jains. The third discusses rebirth and the means to knowledge, the fourth the fruit of liberation (mokṣa). Throughout, Shankara distinguishes the conventional standpoint, where the world and a personal God are real, from the highest standpoint, where only Brahman is, and holds that liberation comes through knowledge rather than ritual action.

It is the classic statement of non-dualism in Indian philosophy, and shows how a radical claim about self and reality is defended through close scriptural reading and hard argument against rival schools.