There are two books with the title Yueshu 樂書 "Book of Music", the first written by the Northern Wei period 北魏 (386-534) master Xin Dufang 信都芳, and the second, a kind of encyclopaedia, by the Song period 宋 (960-1279) scholar Chen Yang 陳暘. Yue shu is also the title of a treatise on music in the universal history Shiji 史記.
Xin Dufang 信都芳, courtesy name Xin Yulin 信玉琳, came from Hejian 河間 (modern Hejian, Hebei) and was an excellent mathematician. He became a retainer of Yuan Yanming 元延明, the Prince of Anfeng 安豐王, together with whom he collected ancient texts on music and commented on them. When the Prince had to flee for political resaons, Xin Dufang continued this work and compiled the book Yueshu. According to the bibliography Jingjizhi 經籍志in the official dynastic history Suishu 隋書, the Yueshu was 7 juan "scrolls" long, but the bibliographic chapters in the histories Jiutangshu 舊唐書 and Xintangshu 新唐書 say, 9 juan. The book thereafter went lost, but 12 fragments were collected by the Qing period 清 (1644-1911) scholar Ma Guohan 馬國翰 from the encyclopedia Taiping yulan 太平御覽. One fragment speaks about pitchpipes, one about ancient music, and the rest about musical instruments. They are included in Ma Guohan's collectaneum Yuhanshanfang jiyi shu 玉函山房輯佚書.
Chen Yang 陳暘, courtesy name Chen Jinzhi 陳晉之, came from Minqing 閩清 (modern Minqing, Fujian) obtained his jinshi degree during the Shaosheng reign 紹聖 (1094-1097) and was Vice Minister of Rites (libu shilang 禮部侍郎). The book Yueshu was compiled when Chen Yang was proofreader (zhengzi 正字) of the Palace Library (mishusheng 秘書省) and was finished in 1101, after fourty years of compilation. It is a sister-book to the Lishu 禮書, a compilation of Chen Yang's older brother Chen Xiangdao 陳祥道, who had originally been entrusted with the compilation of the Yueshu, but was overburdened with the two books. The Yueshu was first printed in 1199. It is 200 juan long and has a special index of 20 juan length. In the first half (juan 1-95, entitled Xunyi 訓義) the author quotes extensively from the Confucian Classics about the Confucian theory and idea of music. Chen Yang annotated and explained each paragraph. The second half of the book (96-200, entitled Yuetulun 樂圖論) is his own theory of music, with a deepgoing explanation of the construction and functioning of the pitchpipes (lülü 律呂), the musical keys (gongdiao 宮調), musical shapes and forms (yuezhang 樂章) through the ages, dance, play (baixi 百戲), musical instruments, the composition of music and its use for certain court and sacrificial rituals, and the music of the "barbarian" peoples. Music instruments are divided according to two different criteria, first the environment of their use (yabu 雅部 "instruments for elegant performances", hubu 胡部 "instruments of the barbarians”, and subu 俗部 "instruments the common folks"), and second, on a lower level, according to the material (called bayin 八音 "eight types of tone", namely metal 金, stone 石, earth 土, leather 革, silk 絲, bamboo 竹, gourd 匏 and wood 木). The whole section mentiones 462 music instruments. This part of the book is richly illustrated. Also in this part, he quotes from older texts, and was therefore highly admired by the bibliographer Chen Zhensun 陳振孫 (Zhizhai shulu jieti 直齋書錄解題). Unfortunatly the text includes a lot of errors, so that the original texts have to be used with great care. Chen Yang's Yueshu is the oldest surviving full text on musical theory in China, except the Huangyou xinyue tuji 皇祐新樂圖記 that also dates from the Song period. The scholarly value of the Yueshu is therefore very high. Lou Yue 樓鑰 has written a critical commentary to the Yueshu called Yueshu zhengwu 樂書正誤. The Yueshu is to be found in the imperial collectaneum Siku quanshu 四庫全書.
Dai Ning 戴寧 (1996). "Yueshu 樂書", in: Zhongguo xueshu mingzhu tiyao 中國學術名著提要, Yishu 藝術卷, Shanghai: Fudan daxue chubanshe, p. 68.
Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, Changchun: Jilin daxue chubanshe, vol. 1, p. 628.
Zhao Hankun 趙含坤 (2005). Zhongguo leishu 中國類書, p. 92. Shijiazhuang: Hebei renmin chubanshe.
Wu Feng 吳楓 (ed. 1987). Jianming Zhongguo guji cidian 簡明中國古籍辭典, Changchun: Jilin wenshi chubanshe, p. 263.