Nearly everybody who visits the Holy Land seems to buy an olivewood carving of the Shepherd with the little lamb upon his shoulder. It is one of the most beloved symbols portraying the nature of Christ to people. But that type of carving is radically different from the representation of the Good Shepherd which has graced the apses of Christian church buildings ever since they were first built. High on my tourist-agenda, when I first visited Rome, was the Church of Santa Costanza, mainly because I had heard a priest describe the "Christ in Glory" mosaic, the oldest Christian mosaic in the Eternal City. It is really a Good Shepherd symbol, because it depicts the risen Christ standing with arm upraised as Peter and Paul flank him; several sheep stand at his feet and are looking up at him. But…