variation

One of the earliest musical forms. A theme or melody is first presented in a straightforward manner and then repeated as often as the composer wishes but each time it is varied in one or more ways. The theme is usually easily recognizable; it may be a popular tune or - as a gesture of respect - the work of a fellow composer; for example, Johannes Brahms's Variations on a Theme by Haydn (1873), based on a theme known as the St Antony Chorale, although it may also be an original composition. The principle of variations has been used in larger-scale and orchestral works by modern composers, for example Arnold Schoenberg's Variations for Orchestra (1928).