*Juliette, ou la clé des songes* is a French-language opera by Bohuslav Martinů, adapted from Georges Neveux’s surrealist play. This volume presents the opera’s libretto alongside material intended to support analysis, appreciation, and contextual understanding of the work. Centered on a bookseller’s encounter with Juliette, the drama unfolds in a dreamlike setting where memory, identity, and desire become unstable. The edition is especially relevant for readers, performers, and listeners interested in twentieth-century opera, French libretto traditions, and the relationship between text, stage action, and musical structure. Its focus on operas, analysis, appreciation, and librettos suggests both a performance-oriented text and a guide for deeper engagement with Martinů’s work.