 Zhu, a harsh critique of Buddhism, synthesised the later metaphysical developments of Confucianism, known as Neo-Confucianism, and his ideas shaped the trajectory of Korean Neo-Confucianism. Additionally, his commentaries on the Four Books (and his re-organisation and re-wording in some cases) were considered “orthodox”, while other interpretations were considered heterodox. Meanwhile, Korean Confucians clearly debated received ideas differently than Confucian scholars in China, and this gives the Korean contribution to Confucianism even greater significance.