The Impromptu Genre

The term "Impromptu" originates from Latin, meaning "unprepared." It is believed that the term was first used in 1822, when two composers coincidentally employed it for their own works simultaneously. As a musical genre, the impromptu has little relation to improvisation as a performance technique. It simply refers to a piece of music that reflects an improvisatory atmosphere, and it emerged as a musical genre in the 19th century. (While the idea of improvisatory music itself is by no means unique to the 19th century, it was previously known by various names such as toccata and capriccio.)

In the first half of the 19th century, the tradition of the impromptu largely followed two main currents:

• One involved continuous variations on popular opera arias or folk melodies, exemplified by composers such as Czerny and Kalkbrenner, with notable works also by Liszt.
• The other comprised lyrical musical content without a specific form, represented by composers like Voříšek and Marschner, who are said to have first used the term, as well as Schubert's impromptus.

However, even though the form is not fixed, many of them adopt an A-B-A arch form.

Chopin inherited the tradition linked to Schubert, leaving behind the Fantaisie-Impromptu and three Impromptus during his middle creative period. All of these exhibit a clear arch form, with the middle section designated as "sostenuto."

In Impromptu No. 1, various ingenious devices are employed to avoid the melody becoming overly constrained by the metrical structure. The right-hand melody is constructed by combining disjunct and conjunct motion, with leaps typically appearing on weak beats. Techniques for shifting melodic accent positions are also diverse; the opening trill already exemplifies this. Furthermore, the syncopated motive appearing in measure 8, the accents often placed on the second beat in the Sostenuto section, and the instruction in measure 23 to group triplet notes in twos, all contribute to this effect.

These remarkably detailed performance instructions are intended to create an improvisatory atmosphere, clearly demonstrating that the impromptu is composed with extremely precise calculation. The light, flowing melody and the perpetual motion accompaniment in the left hand are highly effective, making this work a prime example of the impromptu genre.