Before the Tang Dynasty, Confucianism took the Five Classics as classics, but The Analects of Confucius and Mencius were not officially listed as classics. University and The Doctrine of the Mean are two books in the Book of Rites, which have no special status. Meng and Mengdu began in the Northern Song Dynasty, and the official Notes on Four Books was written by Zhu. Later, the society valued four books over five classics, and the imperial examination took four books as the main subject.
Zhu explained his intention of attaching importance to the four books in the preface of "University Chapters and Sentences" and "Doctrine of the Mean Chapters and Sentences", saying that since the Han and Tang Dynasties, Confucian classics only focused on "reciting chapters and sentences", and Taoism and Buddhism spread heresy, so that Confucianism could not spread after Mencius; The "Four Books" proposed by Cheng and Zhu are just to "imitate Mencius". Zhu believes that "university" is "the method of teaching people in ancient universities", and scholars must learn from it in order to achieve sacred knowledge. He wrote "Supplementary Biography of University Things", emphasizing that "things are poor in reason". "As for the long time of exertion, once it is suddenly penetrated, the surface and surface uses of many things are everywhere, and the use of my heart is unknown." He believes that the golden mean is "Confucius teaches the heart", which clarifies the way of sages, emphasizes the dimension and reveals the meaning. No book is as clear and detailed as The Doctrine of the Mean.
As for The Analects of Confucius and Mencius, Zhu quoted as saying: "Scholars should base themselves on The Analects of Confucius and Mencius. If The Analects of Confucius and Mencius are cured, the Six Classics can be cured and clear. " Zhu admired Mencius and thought that Mencius was a saint, not as good as a saint. From then on, Confucius and Mencius called each other. In The Analects of Confucius, Zhu said: "My wife wants to do everything, and the principle of nature shall prevail", "She has no worries and keeps pace with the world", pointing out the realm pursued by Taoism.
There are many versions of the Notes on Four Books, among which China Bookstore photocopied the Notes on Four Books and Five Classics of Song Dynasty in 1984, and Zhonghua Book Company published the first edition of the Notes on Four Books and the Collection of Newly Edited Scholars in 1983. Focus on reading The Doctrine of the Mean.