In 1819, the Viennese publisher and composer Anton Diabelli sent a waltz he had composed himself in C major to several well-known composers, including Beethoven, Czerny, Hummel, and Schubert. Each was asked to contribute a variation for a planned collected edition. Beethoven initially hesitated, then, as usual, procrastinated, but finally surprised Diabelli with an unexpected gift: a magnificent cycle of 33 variations. The fortunate initiator published Beethoven's work separately in 1823 as "33 Variations on a Waltz by Anton Diabelli, Op. 120."
This work is considered not only Beethoven's greatest achievement in variation form but also one of the most remarkable examples of this genre in the entire history of music. Diabelli's simple and hardly original waltz became the catalyst for unbridled flights of fancy. Beethoven employed all kinds of variations, transforming the simple theme into a monumental work.
Its genesis spanned several years. In 1819, Beethoven initially completed 22 variations, then interrupted his work and devoted himself to other pieces such as the Missa solemnis and the last three piano sonatas. It wasn't until 1823 that he composed another 11 variations on the Diabelli theme. This creative period coincided with a difficult time for Beethoven, marked by health problems and legal disputes over the guardianship of his nephew Karl. The variation project allowed him to work in phases of inspired improvisation and to revise and refine the pieces with great flexibility.