Mozart: Piano Trio in B-flat major, K.502

Wolfgang Amadè Mozart (1756-91) first composed for piano trio—the classic ensemble of violin, cello, and piano—in 1776, when he produced his Divertimento in B-flat major (K.254), a work quite in line with the light trios that were designed as amusements for plays in the mid-eigteenth century. His great and enduring contributions began when he returned to the medium a decade later to produce two piano trios, completed respectively on July 8 (in G major, K.496) and November 18 (in B-flat major, K.502). Three more would follow in 1788; together, his five late piano trios are among the most admired in the piano trio repertory. The 1786 trios arrived in the wake of his opera Le nozze di Figaro and immediately preceded his Prague Symphony. It seems likely that he wrote them with an eye cocked toward their commercial possibilities. This pair was published without delay by Franz Anton Hoffmeister.

It is far from coincidental that the spirit breathed into keyboard trios in the 1780s corresponded with the unquestioned supplanting of the harpsichord by the pianoforte and by important technical advances in piano-building in Vienna. In 1788, Haydn asked his publishers to buy him an up-to-date Schantz piano so that he could craft a new set of piano trios specifically to highlight the capabilities of the latest instruments. His publishers acquiesced. As a noted keyboard virtuoso, Mozart was, if anything, even more attuned to the newly developed subtleties of Viennese pianos, and in the decade he resided in Vienna, from 1781 to 1791, he composed seventeen superlative piano concertos, of which three of the most irreplaceable—those in A major (K.488), C minor (K.491), and C major (K.503) date from the same year as the B-flat major Piano Trio. This was also the period of his two great piano quartets, the second of which (in E-flat major, K.493) preceded our trio by only five months.

The piano occupies a position of primus inter pares in K.502, and for considerable expanses one could imagine this work being easily rendered as a solo concerto, or even a solo sonata. In the tightly constructed opening movement (Allegro), everything is based on a single theme—a very Haydnesque procedure but not so often a Mozartian one. It’s a lighthearted, rather nonchalant melody. (A little motif uttered by the violin does take on a role as a sort of subordinate theme, but the structural weight really is born by the principal melody.) As the movement unrolls we are surprised to find that the theme offers as much opportunity as it does for harmonic and contrapuntal elaboration.

The Larghetto is structured as a relaxed rondo, with the recurring theme seeming prescient of reflective songs in Schubert’s Die schöne Müllerin. The commentator Arthur Cohn accurately seized on its subdued nature when he wrote, “The slow movement is in major, but is itching to go into minor, not tonally, but with the melos itself.” In the finale we find Mozart working out his material through a sonata-rondo form in which the principal theme not only recurs (à la rondo) but is also subjected to exploration through a finely wrought development section (à la sonata)—again with the unassuming melody harboring more possibilities for elaboration than we might have expected at first hearing. The second and third movements of this trio seem not far removed from the piano concertos Mozart was writing at about that time, not only in their formal plans and the flavor of their themes but also in the way which the principal themes are adorned at their repetitions, not merely in the spirit of forthright decoration but as a means of expanding the emotional terrain.—James M. Keller

James M. Keller is longtime Program Annotator of the San Francisco Symphony and the New York Philharmonic. His book Chamber Music: A Listener’s Guide (Oxford University Press) is available in hardcover, paperback, and e-book formats.