Frédéric Chopin

The term Impromptu has little technical meaning. Usually a composition for piano (or, occasionally, another solo instrument) that suggests improvisation, it is often thought of as a work resulting from sudden inspiration. Schubert composed eight impromptus in 1827. Of these, only one sounds improvisational, the others are highly organized, and one is a set of variations. Schumann's impromptus, Op. 5 and Op. 124/9, are also in the form of variations, as is a later piece by Balakirev. Like Schubert's, Chopin's four famous Impromptus are in ternary form (ABA). Similarities between the four works have led some writers to suggest that Chopin thought of the four as a "set" in which each successive impromptu is derived, in an improvisatory fashion, from the previous one.

Chopin composed the Impromptu in A flat major, Op. 29, in 1837, not long after he first met Aurore Dudevant (George Sand). The piece was first printed the same year in Paris. Although Op. 29 was the first impromptu Chopin published, it was the second he composed, and it shows a clear ternary form without the lengthy codas heard in his later ones. However, Chopin does employ a great amount of variation within the sections of the work, especially in the B section.

A triplet rhythm pervades the entire first section of the Impromptu A flat major. The wildly leaping, four-measure melody sounds twice, the second time modified to move swiftly into a contrasting theme. Although the new, chromatically sliding melody is very different from the main theme, Chopin maintains the triplet accompaniment figuration and the two-line texture. After passing through several harmonies, the new theme gives way to a return of the main theme, which is almost immediately altered in a developmental fashion, becoming more aggressive, and finally closes with an insistently repeated figure that builds anticipation. A quiet passage with a bell-like tone provides a transition to the B section.

In section B, Chopin dispenses with the triplet rhythm and frenetic energy of the first part of the impromptu, preferring a lyric, rising melody that moves mostly stepwise and is in F minor, the relative minor of A flat. Chopin's repeat of the initial phrase is decorated with flashy pianistic flourishes. The second phrase of this section appears four times in succession, each time embellished to a greater degree and with altered accompaniment in the left hand. Chopin curbs the energy of the B section only slightly before the return of section A. The triplet rhythm of the nearly note-for-note reprise of the A section ceases only at the very end, when a coda featuring hesitant statements of block chords closes the piece.