Neo-Confucianism of the Han and Tang dynasties is an indispensable part of the history of Chinese philosophy. From Han dynasty Confucians to Tang dynasty Confucians, the study of Confucian classics evolved progressively from textual research to conceptual explanation. A significant sign of this transformation is the book Lunyu Bijie 论语笔解 (A Written Explanation of the Analects), co-authored by Han Yu and Li Ao. Making use of the tremendous room for interpretation within the Analects, the book studied and reorganized the relationship between the study of literature and the Dao and principles. It clearly shows an inevitable development of Confucianism, shifting its focus from phenomena to the nature of the heart-mind in order to comprehend nature and heavenly Dao, both of which cannot be heard (from Confucius).