Haydn the progressive. If you don't know the piano works of Haydn, you don't know Haydn. You are also missing out on a keyboard progenitor whose idiomatic writing for the instrument, though sometimes glancing back to the baroque, can be heard developing all the way through the best works of Mozart, Schubert, and Beethoven.

This Januslike aspect of Haydn comes across beautifully in the lithe, elegant hands of pianist Shai Wosner in a new CD comparing Haydn concertos and capriccios with similar forms taken up much later by Ligeti.

It's a smart pairing of pioneers. Nicholas Collon leads Wosner and the Danish National Symphony Orchestra in Ligeti's plucky, light Piano Concerto from 1988. Its first-movement rhythmic cells repeat and develop in jazzy spirals. But the mood is capricious here, too, and the remaining movements come in turns darker and more fantastic.

Haydn is often thought conservative and predictable. But what happens in the Capriccio (Fantasia) in C? It's all fun and games, a hunting lark, until a phrase trails off and a single note gets held. And held. Has the piece ended? Pianist gone home? If you know Haydn, you know better.

- Peter Dobrin