This term means to review what has been learned and to gain new understanding and new insights. It also means to obtain guidance in the present moment by recalling the past. Wen (温) means to review； gu (故) means knowledge that has been acquired in the past； xin (新) means new and unexplored knowledge. Our predecessors had two main approaches to interpreting this term. According to one approach, reviewing the knowledge acquired in the past and understanding new knowledge should be understood as two actions taking place at the same time. In other words, one gains new knowledge in the course of reviewing the old. According to the other, reviewing the knowledge acquired in the past should be viewed as the basis and precondition for understanding new knowledge. Without reviewing, one would not be able to understand new knowledge. Furthermore, the new knowledge is a development of the old on the basis of rejecting stale and outdated ideas of the past. Today, what this term offers is more than a simple methodology for studying, but rather a fundamental mechanism for the development of an individual, an enterprise, an organization, or even a country. The term expresses a dialectical logic between the old and new, past and present, known and unknown, and inheritance and innovation.

Reviewing what you have acquired and learning anew, this way you can be a teacher for others. (The Analects)