The essay summarizes an extended analysis of relations between text and music in Pierre Boulez's cycle 'Pli selon pli'. Composed in 1958-1964, the cycle consists of three vocal-instrumental pieces and two outer movements which are instrumental, with accidental interventions of the human voice. 'Pli selon pli' draws upon poetic texts of Stéphane Mallarmé, the avant-garde French symbolic author. The composition is an homage to Mallarmé, whose poetic ideals are also Boulez's own. To identify fully the relationship between poetic and musical text, the analysis focuses on three levels: form, semantics, and prosody. First addressing generic relations between the stanza structure of the poems and the musical architecture of the pieces, the analysis then identifies more subtle interrelations between meanings and each verse's intonation and rhythmic structure. Boulez's writings on how to relate music to poetic text serve as a reference point. The analysis reveals that Boulez mostly dismisses simple solutions, rejecting such tools as onomatopoeia, and looks instead for deeper correlations between text and music based on contextual meanings and the mood created by the poetry. The composer's strategy mainly focuses on structure; Boulez builds relations between the poetic and musical text structure through formal devices (stanza divisions), logical structure as related to meaning, and rhythmic structure as related to the intonation of each verse. 'Pli selon pli' may thus be seen as Boulez's answer to Mallarmé's pivotal question whether poetry and music can be related on a deepest level.