The article explores how the neo-Confucianists of the Song and Ming dynasties emphasized the importance of nature and destiny. They used the images of eight tri-grams to represent nature and idea, with specific symbols for spirit, change, destiny, and wisdom. By analyzing various hexagrams, they provided new philosophical interpretations of Yi. Additionally, the article discusses the differing views of CHENG Hao and ZHU Xi on the concept of Yi body in their philosophies.