many composers from the classical, romantic and 20th century classical music periods wrote sets of variations. wolfgang amadeus mozart wrote several, one of which was based on a french folktune which we know in britain as “twinkle, twinkle, little star”. beethoven wrote several wonderful sets of variations. many of them were for piano, but he also used the form in other pieces e.g. the slow movement of his . schubert often wrote variations on tunes from his own songs.