- Elaine Sisman
A form founded on repetition, and as such an outgrowth of a fundamental musical and rhetorical principle, in which a discrete theme is repeated several or many times with various modifications. Identifiable as a formal type from the 16th century, it nonetheless reflects a technique and process important in nearly all music, including music in which the improvised repetition of the strophes of song or dance forms is a part. A theme for variations, rarely shorter than eight or longer than 32 bars, may be a melody, a bass line, a harmonic progression or a complex of such elements. When the theme is brief enough to serve as an ostinato, its repetitions generate a continuously unfolding structure with new figurations and textures at each statement of the theme. When the theme is a self-contained sectional structure, such as a small two-reprise form, its repetitions result in a strophic form in which some elements of the theme change and others remain the same; this is known as ‘theme and variations’. If instead of successive repetitions the variations recur singly or in groups after intervening material (e.g. episodes, another theme and its own variations, a ...