Joseph and Mary and how the providence of God brought it about that the Child was born in Bethlehem. If we had Luke alone, we would conclude that they went directly back to Nazareth from Bethlehem, but Matthew supplements Luke by telling of the slaughter of the infants and the flight into Egypt. It is to be noted that it is not merely Joseph and Mary who bring about the fulfillment of the prophecy that the Christ is to be born in Bethlehem. A Roman emperor who issues an edict is the moving cause.