In a review of 1895, Henry Gauthier-Villars described Claude Debussy’s Prélude à l’après-midi d’un faune as “musique de rêve,” a descriptor that has been attached to Debussy’s style ever since. Partly because of the importance of the Prélude within his compositional development, the distinctive sound of Debussy’s “dream music” has often been understood as a response to the hermetic and difficult literary style of French Symbolists, especially that of Stéphane Mallarmé. Yet Gauthier-Villars’s appellation of “musique de rêve” also invoked a specifically sonic (and largely forgotten) set of cultural reference points, an aural backdrop crucial for understanding Debussy’s early style in the 1880s and early 1890s—the widespread cultivation of the topos of reverie in French music in the final two decades of the nineteenth century. Settings of Baudelaire, Verlaine, and Mallarmé by Debussy and his young contemporaries around 1890 were infused with signifiers of dream and reverie that trace back to salon genres of the 1870s and that cross-pollinated with the harmonic language of the newly fashionable valse lente in the early 1880s. Hearing Debussy’s early works in the context of this reverie topos and its aural kinship to the popular valse lente sheds light on the extent to which the radical idiosyncrasy so vaunted by modernists was constantly evolving in tandem with—and could never truly free itself from—an aural culture defined by mass production, repetition, and cliché.