In what aspects are the musical thoughts of Confucian thinkers in Zhou Dynasty systematically expounded?

There is a systematic exposition in Yue Ji.

Yue Ji occupies an extremely important position in the history of China's music theory. This paper not only expounds the origin and social function of music, but also discusses the relationship between music and ceremony, and discusses the important role of beautiful music in the formation of moral quality.

Yue Ji believes that music is a symbol of morality, and morality can be expressed through music, and etiquette and music are interlinked. Music and politics are also interlinked. You can manage political affairs by combining ceremony and music. Rites and music are the means to control feelings, and music can be used as a tool for social education.

There have been two statements:

1, Ji Le was written by Gongsun Nizi, a disciple of Confucius during the Warring States Period.

This book was acquired by Liu Xiang and Liu Xin in Han Dynasty.

It is generally believed that Yue Ji was written in the Western Han Dynasty, but its ideological data came from the pre-Qin philosophers' talk about music.