Exploring the arrangement and poses of his figures within the arched format, Andrea Sacchi revealed his thought process as he considered options for the physical relationship between Christ and the kneeling Saint Peter. He drew over Saint Peter in red chalk, deliberating whether to make him a bit taller while retaining the same pose. To fill the lower left of the composition, Sacchi faintly sketched in some sheep, which identify the subject as Jesus instructing Saint Peter to "Feed my sheep." (John 21:15-17) This command, putting Peter in charge of the physical and spiritual sustenance of Jesus' flock, the early Christians, is the source of Peter's position as the first pope.
The powerful and wealthy Barberini family, which included Pope Urban VIII as well as several cardinals, commissioned numerous artists to create a series of frescoes illustrating Peter's life for their palazzo. This drawing was one of the many designs produced for the planned wall decorations, but no fresco was ever actually executed.