Yue (乐) is one of the six arts of ancient times, often mentioned together with li (礼 rites / social norms). In contrast to external rules and rites, music touches the emotions and thus can affect human behavior. However, not all music counts as the Confucian yue which must have the effect of making the listener calm and measured so as to willingly behave in accordance with social norms, and thus engage harmoniously with others. Yue is often associated with other forms of ceremonial actions; it is one important way of maintaining proper human relations and encouraging better social practices and customs.
Nothing can replace music for creating social harmony, and nothing can replace rites for determining ethical social differences. Music brings people together in harmony; rites establish roles and relationships. Together they direct human morality. (Xunzi)
Confucius said, “I detest replacing red with purple and disturbing refined classical music with the music of the State of Zheng. I loathe those who overthrow the state with their glib tongues.” (The Analects)