One of Frédéric Chopin most famous masterpiece, the Prelude No. 15 in D-Flat Major, nicknamed “Raindrop”, strikes one at first as an oasis of peace and calm. However, the transition from the bright key of D-Flat Major to the tenebrous C sharp minor brings dark, gloomy, disturbing sonorities. In the semantic interpretation of George Sand, this is the moment when ‘the ghosts of dead monks walk in mournful procession’. Chopin himself – adding the word ‘rainy’ to a pupil’s copy of this music – drew attention to another aspect of this work, namely the relentlessness and monotony with which a single note (always the same) resounds throughout the whole prelude, evoking imitative associations.