The Good Shepherd.  Fresco.  Mid-3rd century AD.

        In the Catacomb of Callixtus in Rome, this fresco symbolizes (perhaps secretly) Jesus as a kindly shepherd, caring for the flock of his followers.  Derived from many biblical sources, including the 23rd Psalm, this kind of image is the most popular in the Christian art of this period.  The "Good Shepherd" as an image of Jesus persisted in Christian art until about 500 AD.