French composer Lili Boulanger (1893-1918) lived and worked at a time of experimentation and change in European musical techniques and aesthetics. Her documented interest in French Symbolist literature, her sheltered, sickly life and her mystic personal beliefs were reflected in a style of composition that grew more subjective as she matured. Analysis of her longest work, the song cycle Clairieres dans le ciel, when amplified by specific information about her life, reveals symbolism that parallels personal meanings contemporary Symbolist artists in literature and painting encoded in their work. Other composers of the period engaged in similar semiotic invention, though the term "Symbolist" is seldom applied to them. When critical hallmarks of Symbolist writings are employed, they support the assignation "Symbolist" to the music of Lili Boulanger.