Athematic music is music that lacks any recognizable melody or theme and thus likewise has no melodic repetition or melodic development. This contrasts with monothematic music, which is based on a single theme, and with polythematic music, which is based on multiple themes. Emerging in the early twentieth century as a way of "liberating" music from the supposedly rigid "schackles" of traditional tonality and harmony, athematic music came into prominence with the development by Arnold Schoenberg of his twelve tone system. Athematic music differs from atonal music in that the latter is music in which there is no feeling of a tonal center or of being in a specific key, although there can be one or multiple discernible melodies.
Athematic music is highly controversial. It has often been praised and encouraged, especially by academics and professional music critics, as being innovative and a major advance in the development of music composition. However, it also has many critics, particularly among non-academic music lovers, many of whom find most of it lacking in any emotional appeal, and just plain boring.