Zhu inherited Mr. Cheng's views and practices, and especially praised The Great Learning and The Doctrine of the Mean in Mencius, making them parallel with The Analects. It is considered that the classics in Da Xue are "the words of Confucius, the narration of Ceng Zi" and the part of "biography" is "the meaning of Ceng Zi, and all his disciples remember it". The doctrine of the mean is a combination of Confucius' teaching the mind and Zi Si Shu's teaching Mencius, which represents a Confucian orthodoxy that Confucius passed on to Mencius through Zeng Shen and Zi Si.
The annotations of Daxue and The Doctrine of the Mean are called "chapters and sentences", and the annotations of The Analects and Mencius are called "concentrated notes" because they quote many quotations from Cheng Cheng's disciples and others. Later generations are collectively referred to as "four books, chapters and sentences" or "four books and notes" for short. So there is the concept of four books. The Four Books was first published by Zhu Yunan in the Song and Yuan Dynasties (1 190). Of course, this is not the final version. Zhu has been revising it.
The day before 7 1 died, he was still revising the notes of the "Honesty" chapter of University. It can be seen that Zhu spent his whole life writing it. Therefore, the four books have become four classic interpretation works. It is far from enough to read Daxue, The Doctrine of the Mean, The Analects of Confucius and Mencius without referring to the notes of the Four Books. Because of this, Zhu's "Notes on Four Books" also became the textbook of imperial examinations in Ming and Qing Dynasties. Regarding the Four Books, Zhu has a saying called "Four Books, the Order of Six Classics". It can be seen that reading four books is the premise of reading six classics. This is still instructive today.