 Zhu Xi was an active scholar-intellectual who held discussions and disputes with other scholars, both in correspondence and in person. His thought can be understood by contrast with the thought of his intellectual rivals as well as through his positive views. For example, his series of letters with Zhang Shi on the topic of self-cultivation and moral psychology, preserved in the Collected Writings of Master Zhu (Zhuzi wenji), provides an illuminating record of these two dedicated Confucians’ quest for a well-grounded, efficacious approach to self-cultivation. He debated with Lü Zuqian (1134–1181) on the nature of education. Zhu focused on the Confucian Way and moral practice in education while Lu argued for a broader-based humanities approach. Zhu held a series of debates with Lu Jiuyuan (Xiangshan: 1139–93) on the nature of realization and moral conduct. Whereas Zhu advocated regimens of study, reflection, observation, and practice, Lu spoke simply of reflecting on self and clarifying the mind, considering that once the mind was clear one would know spontaneously what to do in any situation. Zhu also corresponded with the “utilitarian” Confucian scholar Chen Liang (1143–94), who disputed Zhu’s focus on individual moral realization and the received “Way” with a broader institutional approach that was more sensitive to empirical facts and conditions. Zhu generally eclipsed all of the other scholars of his day, partly because he outlived them and had so many students but mainly because his system was so compelling. It was comprehensive yet nuanced, tightly reasoned yet accommodating of individual differences. It preserved the essential Confucian Way, yet ramified it to meet the challenges of Buddhism and Daoism as spiritual teachings. Zhu’s influence rose at the end of the Southern Song dynasty and became decisive during the Yuan dynasty when his edition of the Four Books was adopted as the basis of the imperial examination system arranged by scholars trained in his approach.