If we cannot see God with our own eyes, for what purpose do we picture God in art? During the Middle Ages, the Second Commandment's warning against idolatry was largely set aside as the power of images became boldly and visibly evident. By the twelfth century, one Byzantine authority could even offer his own revision of the Commandment: "Thou shalt paint the likeness of Christ Himself." How and when, Herbert L. Kessler asks, was the Jewish prohibition...