Among instruments within the evolution of Western art music, the harpsichord has had a unique history. As technological improvements, most significant during the 18th and 19th centuries, led to the creation of more powerful and potentially more expressive instruments, some older instruments became virtually extinct. Examples include the basset horn, which has been replaced by the clarinet, and the ophicleide, whose orchestral parts are now usually covered (inappropriately, some would assert) by a tuba. These older instruments are periodically resuscitated in the interest of historical accuracy (or curiosity), but they remain anachronisms, without a continuing role to play in contemporary composition.
The harpsichord was the dominant keyboard instrument until at least 1750; the great solo keyboard literature by Scarlatti and Bach was almost certainly written with such an instrument in mind. Performances of symphonies by Haydn or Mozart would usually have a harpsichord present, to reinforce the bass line and enhance rhythmic clarity. By 1800, however, precursors to the modern piano had begun to take over, and by the middle of the century, the harpsichord was essentially forgotten, except for a few specialists who occasionally turned to it for "authentic" performances of older works.
What saved the instrument from doom was that its sound was still completely different from that of the instrument that ostensibly "replaced" it, the piano. Inside the instrument, piano strings are struck with a hammer, while harpsichord strings are plucked; the mechanisms are so dissimilar that it is hardly fair to put the two instruments in the same category. The 20th-century interest in leaner sonorities has benefited the harpsichord. While the 19th century produced no examples of music for solo harpsichord, its literature has been growing again during the last 80 or so years, and the instrument has been fully revived. Poulenc's Concert champêtre is dedicated to Wanda Landowska, whose great musicianship inspired many composers to turn their attention to the instrument.
"Champêtre" can be approximately translated as "rustic," and the piece has a general lightness to it that suits the harpsichord's sound well. The lightness extends to the spirit of the piece: Poulenc had a great melodic flair, and did not generally take himself too seriously. Unexpected "wrong" notes appear without harmonic or dramatic consequence, and melodic abundance substitutes for any real motivic development. The orchestration is extremely colorful, and the harpsichord is all but ignored for lengthy stretches, particularly in the finale; yet most of the thematic material is introduced by the harpsichord, confirming the importance of its role as soloist. The first and third movements end under a cloud, in apparent contradiction to the sunny nature of the rest of the piece, but this is probably better understood as ironic humor than as underlying despair.