Since they shared a common feast day, Saints Peter and Paul were often paired together by artists as devotional figures. Here they represent the joint founders of the Christian Church, Peter symbolizing the original Jewish element, Paul the gentile. Tradition records that Peter and Paul were martyred in Rome on the same day: Peter was crucified upside down, but Paul, who was a Roman citizen, was entitled to the more honorable and swifter execution by the sword, an attribute which he holds here. Peter is customarily represented holding the keys to the kingdom of heaven presented to him by Christ. The execution of the two saints takes place in the lower marginal extender. The text reads: Quem me [esse] dicitis dixit Ihesus discipulis suis ("Who am I?" said Jesus to his disciple). The text is the response for the third nocturn in matins for the Feast of Saints Peter and Paul (June 29).
This leaf comes from a manuscript once owned by the famous Victorian art critic, John Ruskin (1819-1900), who is known to have removed some of its leaves to give away as gifts.