"Yiwenzhi" (), or the "Treatise on Literature", is the bibliographical section of the Hanshu (Book of Han) by the Chinese historian Ban Gu (32–92 AD), who completed the work begun by his father Ban Biao. The bibliographical catalog is the last of its ten treatises, and scroll 30 of the 100 scrolls comprising the Hanshu. The basis for the catalog came from Liu Xin's Qilüe (七略), which gives detailed bibliographical information about holdings in the Imperial Library, which itself was an extension on Bielu (別錄) by Liu Xin's father Liu Xiang, on which the two had collaborated. The catalog provides important insights into the literature of the various Chinese intellectual currents of the pre-Qin period (Nine Schools of Thought), of which only some 20% are presently known. Origin of the bibliography "Yiwenzhi" closely adheres to the bibliographical system devised by Liu Xiang and Liu Xin with minor exceptions. The introductory paragraph of the treatise, most likely taken verbatim from Qilue, is quite informative: "Many books were in great disarray in the time of Chengdi, upon which Chen Nong (陳農) was ordered to collect all the books in the world, and high officials to collate books in the Imperial Library; Luminous Grand Master, Liu Xiang, was put in charge of works by the Confucians, the philosophers, and the shi and fu poets; Lieutenant General of the Shanglin Imperial Garden Garrison, Ren Hong (任宏), of works by militarists, Grand Astronomer-Historian, Yin Xian (尹咸), of works by astrologers and diviners, and Surgeon to the Emperor, Li Zhuguo (李柱國), of works by herbalists and alchemists. Liu Xiang wrote an abstract for each completed work, catalogued, and memorialized it to the emperor. Liu Xin expanded the system to cover a great many books, and memorialized the Seven Abstracts, or the Qilue." Liu Xin created a seventh domain Jilue (輯略) to separate books he himself wrote, but Ban Gu, while using Liu Xin's Qilue material, reverted to the six-domain system of Liu Xiang, and reclassified Liu Xin's works into the other six domains. Furthermore, Ban Gu added titles that appeared after Qilue (before 23) and before his time of writing the Hanshu (before 92), including some of his own. Material and morphology of books in the "Yiwenzhi" Scrolls in bamboo strips, mostly for text, were referred to as pian (篇), while those in woven silk, mostly for large pictorial representations, as juan (卷); both are called