Variations on a Theme by Hayden

Wikipedia says: The Variations on a Theme by Joseph Haydn, consisting of a theme in B-flat major, eight variations and a finale, were composed in 1873 by Johannes Brahms. Recent scholarship has revealed that, despite the title of the work, the theme is very unlikely to be by Haydn.It was published in two versions: the variations for two pianos, written first but designated Op. 56b, and the same piece for orchestra, referred to as Op. 56a.

The theme begins with a repeated ten-measure passage which itself consists of two intriguing five-measure phrases, a quirk that is likely to have caught Brahms's attention. Almost without exception, the eight variations follow the phrasal structure of the theme and, though less strictly, the harmonic structure as well. Each has a distinctive character, several calling to mind the forms and techniques of earlier eras, with some displaying a mastery of counterpoint seldom encountered in Romantic music. The finale is a magnificent passacaglia, itself a theme and variations on a ground bass, five measures in length, derived from the principal theme.

If you and some of your friends would like to try playing it yourself, here is the complete score for the orchestral version.