In the middle of the set of 24 preludes in all different keys Op. 11, Scriabin limits himself to use only the diatonic notes of D-flat major in slowly moving melodic lines harmonized in thirds. Needless to say it's a great exercise for legato playing in the left hand, which has to play the thirds before the right hand enters with a soaring but tragic melody.

Video: https://youtu.be/zBdNOsToQbU