The creation, performance, significance, and eventhe definition of music vary according to culture and social context. Music ranges from strictly organized compositions (and their recreation in performance), through improvisationalmusic to aleatoric forms. Music can be divided into genres and subgenres, although the dividing lines and relationships between music genres are often subtle, sometimes open to individualinterpretation, and occasionally controversial. Within "the arts", music may be classified as a performing art, a fine art, and auditory art. There is also a strong connection betweenmusic and mathematics.
To many people in many cultures, music is an important part of their way of life. Ancient Greek and Indian philosophers defined music as tones orderedhorizontally as melodies and vertically as harmonies. Common sayings such as "the harmony of the spheres" and "it is music to my ears" point to the notion that music is often ordered andpleasant to listen to. However, 20th-century composer John Cage thought that any sound can be music, saying, for example, "There is no noise, only sound." Musicologist Jean-JacquesNattiez summarizes the relativist, post-modern viewpoint: "The border between music and noise is always culturally defined—which implies that, even within a single society, this border doesnot always pass through the same place; in short, there is rarely a consensus ... By all accounts there is no single and intercultural universal concept defining what music might be."