The term refers to the five musical notes that rise in pitch, from gong (宫),shang (商),jue (角),zhi (徵),to yu (羽), which correspond roughly to the notes of 1, 2, 3, 5, and 6 in today's numbered musical notation. When a zhi minus is placed before zhi and a gong plus after yu, this pentatonic scale becomes heptatonic. Such division of the musical notes gives rise to a variety of tunes. Although Chinese classical music based on a five-note scale does not vary that much, it retains the beauty of a simple, quiet, and lyrical style. As ancient refined music and folksongs were mostly based on a five-note scale, this term often referred to music in general.
Musical sounds, or simply music, are artistically rhythmical sounds flowing forth from one’s stirring emotions. Ancient Chinese often made a distinction between musical sounds and plain sounds. Sounds created by a natural environment are plain sounds, while those created when emotions well up in one’s heart is music. A single sound is called sheng (声), different sounds that come together are called yin (音); when these sounds beautifully fit together, they are called music (yue 乐). Ancient Chinese believed that musical sounds derive from one's inner motions, and that the music of a country or a region reflects the popular sentiments and the social mores there. Hence Confucian scholars believed that art and literature demonstrate both virtues and flaws in a country's governance and therefore play the role of moral education.
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.