④ Paper books: According to archaeological discoveries, plant fiber paper was invented as early as the early Western Han Dynasty. After Cai Lun of the Eastern Han Dynasty improved papermaking, people

④ Paper books: According to archaeological discoveries, plant fiber paper was invented as early as the early Western Han Dynasty. After Cai Lun of the Eastern Han Dynasty improved papermaking, people began to use paper to write, but bamboo slips and silk books existed at the same time, and they were still the main forms of books. During the Three Kingdoms period, with the improvement of papermaking technology and the emergence of large amounts of paper, paper manuscripts replaced simple volumes and silk books as the main form of books. According to historical records, after Chen Shou's "Three Kingdoms" was written, many people at that time loved to copy it. Zuo Si's "Sandu Fu" was written in Beijing, and the masters passed it down from generation to generation. For a time, "paper was expensive in Luoyang". The earliest extant paper book in my country is the fragmentary volume of "Three Kingdoms" written by Jin people. The binding of paper and books has also undergone a series of changes. Before the Tang Dynasty, scrolls were used, and after the Tang Dynasty, folding appeared, and later loose-leaf binding (vertical binding) was introduced. From the Tang to the Qing Dynasty, folding and loose-leaf binding (thread binding) were the main binding forms. For example, you can see the Ming and Qing Dynasties Memorials (folded) and thread-bound ancient books (collected into volumes). The official documents of the Ming and Qing Dynasties are called memorials because they are folded into volumes.