Fragonard's La Grand Pretre Corésus se sacrifie pour sauver Callirhoë (1765, Paris, Louvre) is Fragonard's last and most important history painting. This study refers to a broad range of sources and influences (Sebastiano Ricci, Giambattista Tiepoli, Guarini's "Il Pastor Fido", Racine, the iconography of the "Arria and Paetus"-theme) which helped to shape the final version of the "Corésus". A somewhat unusual chiaroscuro and a peculiar compositional arrangement (position of the columns) suggest that the beholder is watching a kind of "shadow theatre", perhaps an oniric version. Diderot took up this clue in his famous description the "Salon de 1765". He was moreover the only critic who accepted the androgynic aura of the High Priest.