"Classics and history subset" refers to the four categories of ancient books according to their contents. Some large-scale ancient books series often include these four books and are named after them, such as Sikuquanshu, Sikuquanshu and Sibaoyao. It can be seen that the four categories are of great significance to ancient books. This classification method comes from "The Four Books of Capital, A, B, C, D in turn, and the Four Libraries of Classics and History Subsets" in the Book of the New Tang Dynasty. The four-part classification of "Jing, Shi, Zi and Ji" is the product of China traditional culture. Until today, it is still a key to help us get familiar with ancient books and understand traditional culture.