禮記•樂記》中的「理」範疇頗具討論意義。一方面在理範疇的發展史上，它首先提出了「倫理」一詞。另一方面，它繼莊子之後，較早地使用了「天理」的概念，並增之為「天理人欲」 。在先秦所有理字的涵義中， 〈樂記〉繼承了其中「萬事萬物內在屬性和運行規律」 、 「天命人性之理」 、 「倫理」幾個義項。從學派來看，它雜糅了儒家、道家、墨家等多家思想，而又以儒家思想為主。形成了以理為「體」 ，以禮樂為「相」 ，以移風易俗之施為「用」的「體─相─用」三層融通契合結構。 〈樂記〉之理亦與其他哲學範疇產生密切聯繫，再現了先秦理範疇的思想脈絡。

The category of li as it appears in the Yueji (Record of Music) chapter
of the Liji (Book of Rites) is of considerable significance. On the one hand, the Liji Yueji contains the first instance of the word ‘lunli’ in the history of the category of li. On the other hand, following Zhuangzi, it contains an early use of the concept of tianli (principle of nature) and broadens this to tianli renyu (principle of nature and human desires). From all meanings of the character ‘li’ in the pre-Qin period, the Yueji inherited its aspects of internal property and operational pattern of all things and events, consciousness of destiny and life, and ethics (lunli). From a school perspective, the Yueji blends the thought of the Confucian, Daoist and Mohist schools, yet with Confucianism as its main framework. It moreover builds a three-level tacit structure with li as body (ti), etiquette and music as performance (xiang), and the practice of social traditions and customs as function (yong). Moreover, the Yueji also generates close connections between li and other philosophical categories, thereby revealing the intellectual context of the category of li in the pre-Qin period.