
He gathered the teachings of the Upanishads into the threads that became Vedanta, India's most enduring philosophy.
Badarayana composed the Brahma Sutras, the terse aphorisms that systematize the Upanishads and found the school of Vedanta. The thread he draws is the relation of the self, atman, to the ultimate ground, Brahman, and whether they are one, distinct, or somehow both. The sutras are so compressed that they can barely be read without a commentary, and the great commentators who followed, arguing fiercely over what he meant, generated the central debates of later Indian philosophy. Few sentences in history have been weighed as carefully as his.

“Now, therefore, the inquiry into Brahman.”
Tradition names him Vyasa, compiler of wisdom. He gathered the Upanishads into a single thread of questions about the self and the absolute.
Wove the teachings of the Upanishads into the terse aphorisms that founded the school of Vedanta.
Asked whether atman and Brahman are one, distinct, or somehow both. The sutras are so compressed that every later school fought over their meaning.
Shankara, Ramanuja, and Madhva would build empires of commentary on his few lines. No sentences in India were weighed more carefully.
Shankara's most influential work is a direct commentary on Badarayana's Brahma Sutras, systematizing and extending Badarayana's compressed aphorisms into the full architecture of Advaita Vedanta.
Like Shankara before him, Ramanuja built his entire system as a commentary on Badarayana's Brahma Sutras, arguing that the compressed aphorisms actually support qualified non-dualism rather than Shankara's stricter reading.