The distinguishing resource of meaning in opera is operatic voice—not only opera’s most obvious feature but also the source of its generic identity. To a large extent this voice defines itself as a force of rupture, something nearly impossible for other vocal modalities to assimilate or appropriate. Opera as a genre depends on the difference between its own mode of vocalization and any other. For that reason, the self-reflexive staging of opera’s dependence on this singular voice is also a primary generic feature. Opera recurrently gazes at itself through the mirror of its voice. The potentials and perplexities of this self-marking, or “re-marking,” take exemplary form in scenes from Mozart’s Don Giovanni, Wagner’s Tannhäuser, and John Adams’s Doctor Atomic.