《宋书·志·卷十九》
歌唱与舞蹈，是用来宣泄喜悦之情的，如果喜悦之情缺乏节制，那么就流荡荒乱而走上邪路，所以圣人用宫、商、角、征、羽五声协和人们的本性，用金、石、丝、竹、匏、土、革、木八音来调节人们的流荡，而称它为音乐，所以它有移风易俗、平心正体的作用。
咏哥舞蹈，所以宣其喜心，喜而无节，则流淫莫反。故圣人以五声和其性，以八音节其流，而谓之乐，故能移风易俗，平心正体焉。
Singing and dancing are used to express joy. If joy is not restrained, it will become chaotic and lead to evil, so the sage uses the five sounds of gong, shang, jiao, zheng, and yu to harmonize people's nature and the eight sounds of gold, stone, silk, bamboo, gourd, earth, leather, and wood to regulate people's wandering, and call it music, so it has the effect of changing customs and regulating mind and body.