As the title literally expresses (clear-dark), this piece is inspired by a succession of different intensities of light. The musical recreation of such extra-musical material as light is accounted by a particular and precise use of harmony. Chords are obtained by superposition of equal intervals, i.e. perfect fifths or augmented fourths, and their sonorities are associated to a particular light intensity. The boldness of these chords is then furnished with the addition of whole-tones or semitones, creating a much richer (and hence more complex) harmonic process. A special effect is achieved by using col legno battuto in the violin together with plucked strings in the piano, creating a very startling sonority.