中庸

"The Doctrine of the Mean" is a monograph on moral philosophy in ancient China that discusses the realm of life and cultivation. It originally belonged to the thirty-first chapter of the "Book of Rites" and is one of the Confucian classics. It is said to have been written by Zisi during the Warring States Period. The content affirms that "the mean" is the highest standard of moral behavior, regards "honesty" as the noumenon of the world, believes that "sincere" reaches the highest level of life, and proposes "learned, interrogated, deliberated, discerned , The learning process and method of understanding.
In the Song Dynasty, it was extracted from the "Book of Rites" and combined with "The Daxue", "The Analects" and "Mencius" into the "Four Books". After the Song and Yuan dynasties, it became a school official-appointed textbook and required reading for the imperial examination, which had a great influence on ancient Chinese education and society. The main notes are Cheng Hao's "The Doctrine of the Mean", Cheng Yi's "The Doctrine of the Mean", Zhu Xi's "The Doctrine of the Doctrine of the Mean", Li Yuan's "Annotation to the Doctrine of the Mean", Dai Zhen's Supplementary Notes to the Doctrine of the Mean, Kang Youwei's "Annotation to the Mean", Ma Qichang's "The Doctrine of the Mean" Friendship Interpretation and Hu Huaichen's "A Brief Talk on the Mean" and so on.