Mencius said: "Confucius climbed Mount Meng and thought that the whole country of Lu had become smaller. He climbed Mount Tai and felt that the whole world had become smaller. Therefore, it is hard for people who have seen the sea to see other waters, and it is hard for people who have studied saints to hear other remarks. There are certain ways to see water. You have to watch its big waves first. The sun and the moon can shine into a small gap. This kind of thing, running water, will not advance unless the pit is filled; The ambition of a gentleman, pursuing the avenue, is not accessible until a certain stage. "