Eight variations in A on “Come un’agnello” from the opera “Fra i due litiganti il terzo gode” by Giuseppe Sarti

Variation sets for keyboard instruments enjoyed great popularity in the second half of the 18th century and the first half of the 19th century. While some variations were composed for pedagogical purposes, most of Mozart’s variation works originated from improvisations in which he showcased both his brilliant keyboard technique and his imagination. Standalone variation works are usually based on a preexisting melody and typically consist of 8–12 variations, though occasionally only 5 or 6, with increasing technical difficulty. In contrast, variations that appear within multi-movement works generally include no more than 6 variations, and the themes for these are almost always by Mozart himself. Many of the standalone works end with a fast-tempo variation that contrasts metrically with the theme. This final variation, which may be extended by a coda and often maintains an improvisatory character, is usually preceded by a slow variation, which is often introduced by a variation in the parallel minor key.