A Yale lecture from the course Let This Be a Lesson examines Jean-Léon Gérôme's Ave Caesar! Morituri te salutant, his widely reproduced painting of gladiators saluting before combat in a packed Roman arena. The lecture traces how history painting held its ground in the official Academy and public Salon even as Realism and Impressionism were pulling artists toward everyday subjects and looser brushwork. It places Gérôme's meticulous, almost photographic staging of ancient Rome against the rise of actual photography and early cinema, asking what audiences wanted from historical spectacle once cameras could also produce convincing illusions of the past. The instructor walks through the painting's composition, its sources in classical scholarship, and its afterlife as a visual template later borrowed by Hollywood epics. Eleven lectures into the course, this session uses one canvas to show how a genre under pressure kept finding new justifications for itself.