Shepherd and the Sheep

The young priest was teaching the 23rd psalm-Lord our shepherd -to the Sunday school children. He told them that they were sheep who needed guidance.  Then the priest asked, "If you are the sheep then who is the shepherd-- obviously indicating himself.  A silence of a few seconds followed.  Then a young boy said, "Jesus. Jesus is the shepherd."  The young priest, obviously caught by surprise, said to the boy, "Well then, who am I?"  The boy frowned thoughtfully and then said, "I guess you must be a sheep dog."