Cai Qing is an important scholar majoring in Yi in Ming Dynasty, and his Yijing mengyin has a great influence on Chen Chen and Lin Xi-uan. Cai' s Yijing mengyin is to make clear Chouyi benyi and tends to confirm Zhu Xi' s initiative for studying Yi. Mengyin makes Zhu Xi' s meaning more accurate, and positions Yi to be a great book of distinguishing luck and adversity through moral values, including philosophy and historic events. As for the Supreme Principle (Taichi), Cai transfers Zhu Xi' s static Being of Existence into dynamic and creative formation of the universe. In addition, Cai emphasizes the importance of being integrity under any circumstances by means of meditating and being calm and precautious.