There are four interpretations of "reviewing the past and learning the new". The first is "reviewing the past to learn the new", reviewing the knowledge you have learned and gaining new insights from it; the second is "reviewing the past and learning the new": on the one hand, you must review the classics and stories, and on the other hand, you must strive to acquire new knowledge. The third is to review the past and learn the new. As your experience becomes richer and your understanding improves, you can always learn more when you look back at the knowledge you have read before. Fourth, and what I think is the correct explanation, is that by reviewing history, we can predict and solve future problems. This is what a true master should have.