The text recounts a narrative founded on the 5th-century hagiography the "Legenda S. Silvestri". This fictitious tale describes the sainted Pope Sylvester's rescue of the Romans from the depredations of a local dragon and the pontiff's miraculous cure of the emperor's leprosy by the sacrament of baptism. The story was rehearsed by the "Liber Pontificalis"; by the later 8th century the dragon-slayer Sylvester and his apostolic successors were rewarded in the "Donation of Constantine" with temporal powers never in fact exercised by the historical Bishops of Rome under Constantine"."