The Comprehensive Mirror to Aid in Government (Zizhi tongjian) is the first comprehensive, chronologically-organized history in China. It describes 1,362 years of history, from the 23rd year of King Weilie of the Zhou (403 B.C.) to the sixth year of the Xuande era (959 A.D.) of the Later Zhou dynasty. The entire book comprises 294 juan (sections), with a 30-juan index and a 30-juan “investigation of inconsistencies.” The compiler was Sima Guang (1019–86), assisted by others. Sima Guang (courtesy name Junshi, sobriquet Yusou, commonly called Master of the Su River), was presented as a scholar (jinshi) in the first year of the Baoyuan era (1038) of Emperor Renzong. He occupied a number of important posts, and was posthumously given the name Wenzheng, the office Grand Preceptor, and the feudal title Wenguo Gong. The single juan of the Comprehensive Mirror held by the National Library of China is an original draft written by Sima Guang himself. The work, 33.8 centimeters wide and 130 centimeters long, has over 460 characters in 29 columns, and records the events of the first year of the Yongchang era (322 A.D.) of Emperor Yuan of the Eastern Jin dynasty. The draft is on a letter from Fan Chunren to the author and his older brother, Sima Dan. At the end is a copy of Sima Guang’s “Thank-you to someone for a present.” Following the juan are colophons by persons of the Song and Yuan dynasties. There are over a 100 seals by collectors from the Song to the Qing dynasties.