AbstractTo turn to 1830s London is to explore a time and place newly obsessed with the eye and with lighting technologies. Understanding how opera was experienced at this time, therefore, requires that visuality be brought to the fore. One staging in particular, that ofGustavus the Third, adapted from Daniel Auber’sGustave IIIfor Covent Garden in 1833, reveals how new discussions about light and vision were influencing responses to opera. While London adaptations of Frenchgrands opérasin the nineteenth century have often been dismissed as shabby imitations, critics insisted that the spectacle inGustavusoutstripped anything that had ever been done in Paris. The reason, I propose, was the source and focus of that spectacle: light.