This term refers collectively to the four Confucian classics: The Analects, Mencius, The Great Learning, and The Doctrine of the Mean. The Great Learning and The Doctrine of the Mean originally were two sections of The Book of Rites, but before the Tang Dynasty they did not attract much attention. Following the revival of Confucianism which began in the Tang and Song dynasties, through the advocacy of Han Yu (768-824) and Li Ao (772-836) of the Tang Dynasty, Cheng Hao (1032-1085), Cheng Yi (1033-1107) and Zhu Xi (1130-1200) of the Song Dynasty, The Great Learning and The Doctrine of the Mean were given new meaning. Their standing was gradually elevated, and they were regarded just as important as The Analects and Mencius. The four were then collectively known as the Four Books. Commentaries on the Four Books, written by Zhu Xi, established the dominant position of the Four Books, which formed the foundation for the neo-Confucian scholars of the Song and Ming dynasties. The Four Books became the source from which the neo-Confucian scholars drew inspiration to further their learning, and thus exerted a profound influence on the development of Confucianism.

The principles in the Four Books, i.e., The Great Learning, The Doctrine of the Mean, The Analects, and Mencius, are illuminating and easy to follow.  (Categorized Conversations of Master Zhu Xi)