This article explores intersections of embodied cognition and form in Gérard Grisey's Prologue pour alto seul (1976). Drawing on work in mimetic imagery, gestural cognition, and body-based conceptualization, I trace Prologue 's seemingly abstract processes of variation, opposition, and tension to the performer's actions and an embodied listener's responses to those actions. My analysis demonstrates how Prologue relies on the body as a medium and metaphor for its structuring, from Grisey's bodily metaphors for its motives to listeners' responses to its boisterous and noisy climactic section. By concentrating on performance and embodiment concerns, I aim in my analysis to bring out the implicit role of bodies and materials in spectral theory and discourse more broadly. In conclusion, I reconsider the commonly held notion that spectral music is "about" sound in light of the close associations of sound with movement and action identified by embodied cognition.