Leishu

The leishu () is a genre of reference books historically compiled in China and other East Asian countries. The term is generally translated as "encyclopedia", although the "leishu" are quite different from the modern notion of encyclopedia.
The "leishu" are composed of sometimes lengthy citations from other works, and often contain copies of entire works, not just excerpts. The works are classified by a systematic set of categories, which are further divided into subcategories. "Leishu" may be considered anthologies, but are encyclopedic in the sense that they may comprise the entire realm of knowledge at the time of compilation.
Approximately 600 "leishu" were compiled from the early third century until the eighteenth century, of which 200 have survived. The largest "leishu" ever compiled was the 1408 "Yongle Encyclopedia", containing 370 million Chinese characters, and the largest ever printed was the "Gujin Tushu Jicheng", containing 100 million characters and 852,408 pages.
History.
The genre first appeared in the early third century. The earliest known was the "Huanglan" ("Emperor's mirror"). Sponsored by the emperor of Cao Wei, it was compiled around 220, but has since been lost. However, the term "leishu" was not used until the Song dynasty (960–1279).
In later imperial China dynasties, such as the Ming and Qing, emperors sponsored monumental projects to compile all known human knowledge into a single "leishu", in which entire works, rather than excerpts, were copied and classified by category. The largest "leishu" ever compiled, on the order of the Yongle Emperor of Ming, was the "Yongle Dadian" containing a total of 370 million Chinese characters. The project involved 2,169 scholars, who worked for four years under general editor Yao Guangxiao. It was completed in 1408, but never printed, as the imperial treasury had run out of money.
The "Qinding Gujin Tushu Jicheng" (Imperially approved synthesis of books and illustrations past and present) is by far the largest "leishu" ever printed, containing 100 million characters and 852,408 pages. It was compiled by a team of scholars led by Chen Menglei, and printed between 1726 and 1728, during the Qing dynasty.
The "riyong leishu" (encyclopedias for daily use), containing practical information for people who were literate but below the Confucian elite, were also compiled in the later imperial era. Today, they provide scholars with valuable information on non-elite culture and attitudes.
According to Jean-Pierre Diény, the Jiaqing reign (1796–1820) of the Qing dynasty saw the end of the publication of "leishu".
In other countries.
Other countries in East Asia also adopted the genre of "leishu". In 1712, the "Sancai Tuhui", a richly illustrated "leishu" compiled by Ming scholar Wang Qi () in the early 17th century, was printed in Japan as "Wakan Sansai Zue". The Japanese version was edited by Terajima Ryōan (), a physician born in Osaka.
Importance.
The "leishu" have played an important role in the preservation of ancient works, many of which have been lost, only preserved completely or partially as part of a "leishu" compilation. The 7th-century "Yiwen Leiju" is especially valuable. It contains excerpts from 1,400 pre-7th century works, 90% of which have been otherwise lost. Even though the "Yongle Dadian" is itself largely lost, the remnants still contain 385 complete books that have been otherwise lost. The "leishu" also provide a unique view of the transmission of knowledge and education, and an easy way to locate traditional materials on any given subject.
Major compilations.
Approximately 600 "leishu" were compiled, from the Cao Wei period (early third century) until the 18th century, of which 200 have survived. Among the most important, in chronological order, are: