Mass of Saint Gregory

The Mass of Saint Gregory is a significant subject in Roman Catholic art, depicting Pope Gregory I during a Mass with a vision of Christ appearing on the consecrated host to convince a doubting deacon of the doctrine of transubstantiation. The story's origins can be traced back to 8th-century biographies by Paul and John the Deacon, which evolved over time. By the 13th century, the Golden Legend transformed the doubter into a deacon and the host into a full Christ figure. The image gained widespread popularity after its display during the Jubilee Year of 1350 in Rome, leading to its use as altarpieces and illuminated manuscript illustrations across Europe. The iconography often features Christ as the Man of Sorrows, with Instruments of the Passion on the altar and flowing blood into the chalice. Larger works include depictions of the deacon and donor portraits. Despite the Protestant Reformation, the image remained a powerful symbol for Catholics, reinforcing both Papal authority and transubstantiation.