The overwhelming presumption about songs is that they are meant to be sung. In the curious case of “En Sourdine” (“Muted”; 1904), composed by Pau Casals (1876–1973), we see an exquisite discrepancy: a love song that is both romantic utterance and yet muteness. The paradoxical genesis of “En Sourdine” stems from Casals’s then secretive relationship with lieder singer, Susan Metcalfe, during their performance engagements in and around New York City circa 1904. In “Musicology for Art Historians”, Jonathan Hicks tells us that musicology relentlessly promoted the association of “composerly authority with a masculine subject.” This focus obfuscated many aspects of compositional impetus and relegated the role of other historical agents to oblivion, particularly the roles of “singer, instrumentalist, patron, etc.—that women have most often been in positions to perform.” “En Sourdine,” a song that significantly appears in Casals’s catalog without a date, reveals the deeply personal nature of his vocal works. An analysis of “En Sourdine” reveals the song’s function as a form of sensual communication, not intended for public dissemination. This study contributes to a reassessment of the role of singer and muse, as well as a discussion of one of Casals’s 34 songs.