The Doctrine of the Mean, originally the thirty-first article in The Book of Rites, is an article on Confucian human nature cultivation. It is said that it was written by Zisi, which is an important monograph on educational theory in ancient China. Respected by Cheng Hao and Cheng Yi in the Northern Song Dynasty, Zhu in the Southern Song Dynasty wrote Notes on the Doctrine of the Mean, which was finally called "Four Books" together with Daxue, Analects of Confucius and Mencius. After the Song and Yuan Dynasties, The Doctrine of the Mean became an official textbook and a must-read in the imperial examination, which had a great influence on ancient education.

The main purpose of The Doctrine of the Mean is to educate people in self-cultivation, self-supervision, self-education and self-improvement, to cultivate themselves into ideal people with ideal personality, to achieve the realm of perfection, benevolence, sincerity, morality, holiness and external integration, and to create the realm of "harmony but difference, heaven's position and education of everything".

"Destiny is nature, frankness is Tao, cultivation is teaching", which simply reveals that the core of the golden mean theme is self-education. "The nature of destiny" refers to the goodness of human nature. "Follow nature as the Tao" means that people's way of self-education is to do things according to their good nature. "Practice is teaching" means that self-education is to practice according to the principle of human nature. "Tao also, not from also, can also from the Tao. So a gentleman is wary of what he can't see, and fear is almost unheard of. Can't see the distance, don't show it. Therefore, the gentleman is cautious and independent. " Self-education runs through a person's life, and people can't live without self-education for a moment. To run self-education through the whole process of life, we need strong spirit of self-discipline and self-supervision. This spirit is called prudence and independence. "Emotions and sorrows are not expressed in the festival", which reveals the goals of self-education, self-discipline and self-supervision. "If you are in the middle, it is the foundation of the world; Harmony also means that the world can reach Tao, which points out the great significance of the goal of self-education. " To be neutral, the position of heaven is not good, and everything is nurtured "is a tribute to the infinite merits after achieving the ideal goal of self-education, that is, the effect after having the moral character of benevolence, kindness, honesty, morality and holiness." Neutralization is the realization of self-worth and the embodiment of social value.

The theoretical basis of the doctrine of the mean is the unity of man and nature. The essence of the unity of heaven and man is to be united in sincerity and goodness, to achieve "harmony, the position of heaven and the cultivation of all things" and "only the sincerity of the world, to do our best." If you can do your best, you can do your best; If you can make good use of human nature, you can make good use of things; If you can make the best use of it, you can praise the teaching of heaven and earth; If you can praise the cultivation of heaven and earth, you can participate in it. "Participating with heaven and earth" means the unity of heaven and man.

(1) Heaven and man are one. Heaven is honesty, and humanity is the pursuit of honesty. This is the original intention of the enlightenment of heaven, and try our best to integrate with heaven. In other words, human nature should be consistent with heaven.

(2) Nature and humanity are integrated. The purpose of harmony between man and nature is harmony between man and nature. Nature is kindness, sincerity, benevolence and truth, so should human nature. Only by making human nature reach the nature of goodness, sincerity, benevolence and truth can it be called the true unity of heaven and man, create the outline of the world, establish the foundation of the world, understand the truth of heaven and earth, and achieve the golden mean.

(3) the unity of reason and emotion. People's joys and sorrows are the natural attributes of people and the expression of emotions. In order to pursue the truth, goodness and beauty of human nature, it is necessary to restrain and limit emotions. Therefore, the Doctrine of the Mean says: "Emotion is not expressed in the middle, but in the middle". Only by "neutralization" can we achieve harmony between man and nature ("heaven has no place, and everything can be nurtured")

(4) the integration of ghosts and gods and saints. The Doctrine of the Mean: "Therefore, the way of a gentleman is also ... this is the rule of the world." There is no doubt about the questioning of ghosts and gods, even if you know the sky; When the saints come out after a hundred generations, there will be no doubt, even if you know someone. Explain the golden mean. Heaven in the unity of heaven and man includes ghosts and gods, and man includes saints.

5] external and internal integration. The golden mean: "a sincere person ... therefore, it is appropriate to take measures at the right time." The combination of exterior and interior is the combination of exterior and interior, and the exterior and interior are sincere. Therefore, the doctrine of the mean is the unity of heaven and man, and it is also the unity of sincerity. This unity of external and internal can be regarded as the unity of moral consciousness and moral behavior, or the unity of self and achievement, or the unity of knowing and doing.