In accordance with this genre created by Franz Schubert, the four impromptu works by Chopin show a strong improvisational character while always remaining perfectly light and elegant. These qualities apply in particular to the first three pieces of this volume, opus 29, 36 and 51. While the first of them probably dates from 1837, op. 36 was composed in 1839 and opus 51 three years later, during Chopin's stay at Nohant's estate belonging to the writer George Sand with whom he had a romantic relationship. The opus number of Fantaisie-Impromptu op. 66 is misleading because it was composed in 1834, before the other three impromptu. Chopin had obviously not planned to have it published, but his friend Julian Fontana undertook to do so after the composer's death. The printed version, however, shows such significant differences from the happily preserved autograph manuscript that the Henle-Urtext edition reproduces both versions.