Taking its cue from the problem of formal closure in musical modernity in general and Salvatore Sciarrino’s interpretations of two works by Anton Webern (orchestral pieces op. 6, no. 4 and op. 10, no. 4) in particular, this essay discusses a broad number of Sciarrino’s works as reflections of historical and semantic modes of musical listening and understanding. Emerging from a type of composing based on a comprehensive theory of perception, these works aim at problematizing and deferring the boundaries between musical and everyday listening. Sciarrino’s readings of Webern point us at musical situations, where conventional formal functions of beginning, middle, and ending are no longer evident. Later achievements of serial and postserial music radicalize such a re-definition of musical temporality while continuing to employ elements of conventional trajectories of musical form. Analytical discussions of Sciarrino’s music-theatrical works (Vanitas, Lohengrin, Infinito nero, Luci mie traditrici), orchestral music (Autoritratto nella notte, Efebo con radio), and chamber music (Introduzione all’oscuro, Raffigurar Narciso al fonte, Lo spazio inverso, Omaggio à Burri, Muro d’orizzonte) show how changing constellations of duration, density of information, and types of (open) closure communicate particularly evident and transparent “markings” of a semanticized musical material. Retained difference, open questions, and unresolved conflicts revealed in the final moments of these works reflect formal fissures and topical impasses, making them keys to an understanding of the composer’s unique staging of reflexive musical form.