Fantaisie Impromptu in C# Minor was written in 1834, but never published in the lifetime of its author. Doubtless the most fascinating of Chopin’s posthumous works, it is one of his most well loved and performed pieces. For generations since it was published in 1855, this captivating piece has enthralled audiences the world over.
A quick analysis throws up a few reasons. A fast 4-on-3 polyrhythm introduction reminiscent of the rise and ebb of the ocean, a slow expressive middle portion(which has been used as the basis for the Vaudeville tune “I’m always chasing rainbows”), and of relatively short length coming in at around 5 minutes. It’s played fast but sounds even faster.
It is possibly the most spectacularly dazzling piano work exhibiting the Moire Effect in music, a result of the repetitive 4-on-3 superimposition throughout the piece.
James Huneker, in his landmark book “Chopin: The man and his music”, has described it thus: ”There seems no danger that this Fantaisie-Impromptu will suffer from neglect, for it is the joy of the piano student, who turns its presto into a slow, blurred mess of badly related rhythms, and its slower movement into a long drawn sentimental agony; but in the hands of a master the C sharp minor Impromptu is charming, though not of great depth”.