 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.