This panel portrays Saint John the Apostle on the island of Patmos, intent on writing the Apocalypse, as suggested by the books represented in the left section of the work. In all likelihood, the panel was handmade by an unknown master glassmaker from the mid-16th century - perhaps based on a cartoon by Giorgio d'Anversa - comes from the Duomo's apse window V20, dedicated to episodes from the Book of Revelation. The work has been part of the Duomo Museum's collection since 1974.