In the autumn of 1167, Zhu Xi traveled roughly a thousand kilometers from his own academy to Yuelu specifically to debate Zhang Shi, a rival scholar whose interpretation of the Confucian classics differed from his own on questions that were not merely academic: what human nature fundamentally is, how moral cultivation actually proceeds, and whether understanding must come before right action or whether the two develop together. The two men and their students argued for roughly two months, a sustained, face to face philosophical engagement unusual even by the standards of a tradition that valued debate, and later called simply the Meeting at Yuelu, treated by subsequent generations as a defining episode in the formation of what would become Neo-Confucian orthodoxy.
Zhu Xi did not simply win the argument and leave with his positions unchanged; his later synthesis, the version of Confucian philosophy that would go on to dominate Chinese, Korean and Japanese intellectual life for the next seven centuries and serve as the basis of the imperial examination curriculum, absorbed and responded to positions Zhang Shi pressed him on at Yuelu. That makes the academy's halls, rather than any single text, the physical setting where two of the era's sharpest minds worked out, in real time and in each other's company, disagreements that print alone rarely resolves as thoroughly as sustained oral argument between committed rivals.