Yuelun 樂論 is a treatise of musical philosophy written by Ruan Ji 阮籍 (210-263), one of the Seven Masters of the Bamboo Grove (zhulin qixian 竹林七賢). Another text of this title constitutes the chapter Yuelun 樂論 of the book Xunzi 荀子.
Ruan was famous as a master zither player and created the tune Youwang 酒狂 which is still known today. His essay on music shows his philosophical attitude which attempted to merge Confucian with Daoist concepts. It is composed as a dialogue in which "Master Ruan" (Ruan Xiansheng 阮先生) answers the question of Liuzi 劉子.
Talking about the Confucian aspect of music, its relation to governance must be highlighted. No government tool was so efficient to "change the customs and improve the habits" as music was (yi feng yi su, mo shan yu yue 移風易俗，莫善於樂). From a Daoist aspect, music is seen as an expression of "the way of nature" (ziran zhi dao 自然之道), an embodiment of Heaven and earth, the character of the ten thousand beings.
If Heaven and earth are unified and the characters of all beings moved, there will be harmony. If the pitch pipes (lülü 律呂) were properly tuned, they mirrored the harmony of Yin and Yang. If the sounds and timbres were rightly adjusted, the ten thousand beings were in the right order. Male and female had the right place, and lord and minister their accurate status.
In a disorderly world, the Saints would first tune the sounds harmoniously in order to create rhythm for all (governmental) affairs and incite the obedience of subjects. In that way, "no one would not be without a sense for propriety" (mo bu yi yan 莫不儀焉). The people would compose songs to laud the virtue of the former kings, and learn from them. All (ritual) objects would have the shape as determined by the former kings, and numbers used in ceremonies and usages would correspond to their system. This was because music entered the heart and submerged in the vital energy (qi 氣), where it transformed into a proper attitude.
The eight timbres of music (bayin 八音) had a physis of their own, and the five notes (wusheng 五聲) possessed a nature of their own – all in unison with the ten thousand beings, so that there would be no disturbance in music. The small zither (qin 琴), the large zither (se 瑟), the flute (guan 管), and the soundstones (qing 磬), were related to trees, clouds, bamboos, and the sea, respectively, in harmony and purity (diao he chun jun 調和淳均). Harmonies and relations among pitch pipes and the musical instruments followed the steadiness of nature, and were, with their stable positions (chang chu 常處), able to create harmony and stability in government and society.
The four proper and indispensable tools for governance were thus rites (li 禮), music (yue 樂), penalties (xing 刑), and instructions (jiao 教). Rites meant the observation of social status. Music meant insouciance in life. Rites determined external forms, while music pacified the heart.
"Correct music" (zhengyue 正樂) was to be discerned from "insolent sounds" (yinsheng 淫聲). It had to surpass the pure taste of ears and eyes and to establish a connection between the energies (qi) of Heaven and earth, to tranquilise the spirits of the ten thousand beings, to fix social positions, and make veritable the true nature of men. Thus, in the Hallowed Temple (qingmiao 清廟), successes of virtue were chanted, the songs of the royal banquets praised the principles of comity, and the common folks changed their habits and pursued the path of virtue.
The Yuelun is transmitted as as quotations in various encyclopaedias, like Chuxueji 初學記, Beitang shuchao 北堂書鈔, Yiwen leiju 藝文類聚 and Taiping yulan 太平御覽. It is included in Yan Kejun's 嚴可均 (1762—1843) collection Quan sanguo wen 全三國文, as well as the collected works of the author, Ruan Ji shiwen ji 阮籍詩文集 (Ruan Sizong ji 阮嗣宗集, Ruan Bubing ji 阮步兵集, Ruan Ji ji 阮籍集), the collections Liuchao shiji 六朝詩集, Han-Wei zhu mingjia ji 漢魏諸名家集 and Han-Wei-Liuchao baisan mingjia ji 漢魏六朝百三名家集.