THEME AND VARIATIONS:

This form is widely used in the classical period, either as an independent piece or as one movement of a symphony, a sonata, or a string quartet. In theme and variations, a basic musical idea-the theme-is repeated over and over and is changed each time it is repeated.

Each variation, though usually about the same length as the theme, is unique and may differ in mood from the theme. Changes of melody, rhythm, harmony, accompaniment, dynamics, or tone colour may be used to give a variation its own identity. The core melody may appear in the bass, or it may be repeated in a minor key instead of a major one. It may be heard together with a new melody. The variations may be connected to each other or separated by pauses. For the theme itself, a composer may invent an original melody or borrow someone else's.