“Knowledge” refers to awareness and examination of the principles underlying human relations in everyday life, and “application” refers to the implementation of these principles in everyday life. “Knowledge and application,” used in ancient China, were not in the general sense of having knowledge of external objects, or taking action to utilize and transform external things. Rather, they were recognition and application of principles underlying human relations in everyday life. One acquires “knowledge” in different ways: through visual perception, hearing, or mental reflection and insight. Some people think that “knowledge” is difficult and that “application” is easy. Some think that “knowledge” is easy and that “application” is difficult. Some think that “knowledge” and “application” are equally difficult. As for the relationship between “knowledge” and “application”, some maintain that knowledge and application are united as one. Others think that knowledge and application are separate. These varied understanding of “knowledge and application” determine different ways of fostering virtue and of instruction concerning human relations.

To know is not the hard part; to apply is. (Zuo’s Commentary on The Spring and Autumn Annals)

Not having heard something is not as good as having heard it; having heard it is not as good as having seen it; having seen it is not as good as knowing it; knowing it is not as good as putting it into practice. Learning reaches the ultimate stage when it is being applied. (Xunzi)