The Liberation of St. Peter

map3_iii2The Liberation of St Peter shows the prince of the apostles and first Pope, miraculously saved from prison [after Christ’s crucifixion] by an angel while the guards lie sleeping (Acts of the Apostles 12:5-12).

The scene is a reference to Julius II (pontiff from 1503 to 1513), who before being elected Pope was the titular cardinal of St Peter in Chains. In the celebration of light Raphael confronts the divine light of the angel with that of the dawn, of the moon, of the torches and of their reflections on the armour, and even of the natural light that enters from the window below, creating the most extraordinary effects.

text copied from here