Lili Boulanger chose Francis Jammes' "Tristesses" for her song cycle, "Clairières dans le ciel,".  

Francis Jammes' poetry, while loosely categorized as Symbolist, offers a distinct style: spare, clear, and highly visual, rooted in the tradition of medieval courtly love. This tradition explores themes of obsessive love, unresponsive beloveds, and the poet's suffering, particularly upon the beloved's loss.

Lili, grappling with her own isolation and health struggles, likely identified strongly with the female figure in Jammes' poems. This identification, coupled with the poetry's potential for both sensual and subtle religious interpretations, likely drew her to "Tristesses." 

However, Boulanger did not merely set the poems to music. She significantly reimagined the cycle. She replaced the original title, "Tristesses," with "Clairières dans le ciel" ("Clearings in the Sky"), introducing a note of hope. Furthermore, she selected only thirteen poems from the original twenty-four, omitting several love poems and carefully reordering the chosen ones. 

This deliberate selection and arrangement creates a powerful narrative arc, culminating in a peak of love "Nous nous aimerons tant" (“We shall love each other”) before descending into the poignant despair of the final song, "Demain fera un an" ("Tomorrow it will be a year"); demonstrates Boulanger's artistic agency and her ability to transform the source material into a deeply personal and expressive work.