The altarpiece depicts Tolle Lege, "take up and read", the story of the conversion of the Saint. This an early work by Carlo Maratta, and shows the saint as a monk contemplating an infant. The scene depicts an event which the saint recorded in his autobiography, whereby he heard a child chanting tolle, lege ("take, read") while in a garden. He picked up the Scriptures, and what he read converted him to a fully Christian life.