Feux follets

For the natural phenomenon of 'ghostly lights' see Will-o'-the-wisp. Transcendental Etude No. 5 in B-flat "Feux Follets" (Will o' the Wisp) is the fifth etude  of the set of twelve Transcendental Etudes by Franz Liszt. Feux Follets is one of the most difficult works written for piano. It employs many pianistic devices, rapid double-notes in the right hand foremost among them. Despite the mechanical difficulties of the work, its greatest challenge lies in doing justice to its whimsical and mysterious character. Pianissimo markings abound in the double note sections, countering the pianist's intuition (and desire) to play them loudly. Indeed, to the uninitiated or musically illiterate, Feux Follets is not an impressive, boisterous work, and does not rouse the audience to a pitch of hysteria. Feux Follets is considered one of the great achievements in the pianistic canon.
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[Folklore] Feux follets are little tricky spirits who live in bogs and ponds around Québec. They look like little blue flames and they try to lure travellers into ponds to drown them.