The works to be discussed in this chapter include three of Debussy's greatest pieces for orchestra, all of them explicitly evocative: the Nocturnes, La mer and ‘Ibéria’ from the orchestral Images. In addition, the three piano pieces composed at about the same time as Lamer–Masques, D'un cahier d'esquisses and L'isle joyeuse – will be considered from the point of view of Debussy's expressive intentions. Among his orchestral works, the score of ‘Ibéria’, in particular, is teeming with expression marks which give important clues to the atmospheric evocation he sought to achieve – an innovative practice at the time and one which has sometimes been misunderstood as the quest for a rather generalised kind of poetic or naturalistic allusiveness in music, or simply a vaguely defined effect. But the very precision of Debussy's performance instructions in this instance suggests an entirely different interpretation: that as he refined his command of music's expressive potential, so his intentions were not only to give indications of tempo, dynamics and articulation, but also to specify the emotional and expressive content of a note, a phrase, a section or even a whole piece. For other works the scores themselves contain many fewer clues, but valuable evidence of Debussy's expressive and musical thought processes can be found in his letters and writings – both rich seams of self-revelation.