Mozart composed his Piano Concerto No. 21 in C Major during 1785, a remarkably productive period when he was establishing himself as Vienna's preeminent composer. The "Elvira Madigan" movement takes its nickname from a 1967 Swedish film that featured the piece, though Mozart would never have known this title; he simply called it the Andante.
Mozart's clarinet writing across his concertos and chamber works set the standard for how the instrument could sing. He understood the clarinet's lyrical capabilities and wrote for it with an intimacy that transformed how composers viewed the instrument's role beyond the orchestra.