The Doctrine of the Mean is one of the classics of Chinese Confucianism. It was originally the 31st chapter of the Book of Rites and was said to be written by Kong Ji (Zisi) during the Warring States Period. Its content affirms that the Doctrine of the Mean is the highest standard of moral behavior, regards “sincerity” as the ontology of the world, and believes that “utmost sincerity” reaches the highest realm of life. It also proposes the learning process and cognitive method of “learning extensively, questioning carefully, thinking carefully, distinguishing clearly, and practicing diligently”. In the Song Dynasty, it was extracted from the Book of Rites and combined with The Great Learning, The Analects of Confucius, and Mencius to form the “Four Books”. After the Song and Yuan Dynasties, it became an official textbook for schools and a must-read for the imperial examinations, which had a great influence on ancient Chinese education.
《中庸》是中国儒家经典之一，原是《礼记》第三十一篇，相传为战国时期孔伋（子思）所作。其内容肯定“中庸”是道德行为的最高标准，把“诚”看成是世界的本体，认为“至诚”则达到人生的最高境界，并提出“博学之，审问之，慎思之，明辨之，笃行之”的学习过程和认识方法。宋代从《礼记》中抽出，与《大学》《论语》《孟子》合为“四书”。宋元以后，成为学校官定的教科书和科举考试的必读书，对中国古代教育产生了极大的影响。
中庸·二十五
诚者，自成也；而道，自道也。诚者，物之终始；不诚，无物。是故，君子诚之为贵。诚者，非自成己而已也，所以成物也。成己，仁也；成物，知也。性之德也，合外内之道也，故时措之宜也。
XXV
Truth means the realisation of our being; and moral law means the law of our being. Truth is the beginning and end (the substance) of existence. Without truth there is no existence. It is for this reason that the moral man values truth.
Truth is not only the realisation of our own being. It is that by which things outside of us have an existence. The realisation of our being is moral sense. The realisation of things outside of us is intellect. These, moral sense and intellect, are the powers or faculties of our being. They combine the inner or subjective and outer or objective use of the power of the mind. Therefore with truth, everything done is right.
