L variatio, = change. A composition in which a given theme, or one freely invented by the composer, is altered and adapted in a series of different versions.Variations play an extensive role in Beethovens compositions. He wrote alone over 20 variations for piano, including the Thirty-three Variations for Piano on a Waltz by Diabelli, op. 120 and the Prometheus Variations, op. 35. Beethoven not only wrote variation cycles for piano, but also for other combinations of instruments. Variations do not necessarily have to be compositions in their own right; Beethoven added them as movements to other works nine times.