Piano Trio in A flat major H.XV/14 (1790)

When Haydn wrote his Piano Trio in A flat, not long    before his first visit to London in 1791, Mozart’s piano trios had been in print for two years. If any proof were needed that the modern piano, violin and cello could converse together on something approaching equal terms, there it was – even if the piano was still the dominant voice and the violin still more prominent than the cello. Haydn persisted, however, in treating the piano trio as, at best, a duo for an accomplished pianist and a modest violinist, relegating the cellist for the most part to the unglamorous task of doubling the piano bass line.

The Piano Trio in A flat favours the piano to such an extent that Mozart’s star pupil, the then 13-year-old Johann Nepomuk Hummel, was invited to play it, with Salomon on violin, in one of Haydn’s concerts in the Hanover Square Rooms in 1792. His performance was so impressive that, the story goes, the composer lifted him up, kissed him, and declared him a genius. Flattered by that no doubt, the young pianist must also have been amazed by harmonic events that even Mozart would not have dared. The development section of the first movement, for example, has scarcely begun before it seems to lose its sense of direction and falls into a two-bar silence. The way out, the piano suggests, is by way of G flat major, which is an extraordinary idea in an A flat major context – but not quite as eccentric as the piano’s decision to start the recapitulation in B major. It is only after another, shorter pause that the three instruments light on A flat major for an authentic recapitulation.

The outer sections of the Adagio feature a lovely violin melody in E major and are offset by an elaborately expressive piano solo accompanied by pizzicato strings in the E minor middle section. Rather than bringing the slow movement to a formal ending Haydn contrives to link the closing Vivace directly to it, introducing the main theme on violin and piano in octaves. Somewhere between sonata form and rondo, the last movement thrives happily on the exuberance of that melody, which is shared equally between violin and piano but, inevitably, withheld from the cello.