Ambrose of Milan
Catena Aurea · Lukasevangelium 2
And it came to pass in those days, that there went out a decree from Cæsar Augustus, that all the world should be taxed. (And this taxing was first made when Cyrenius was governor of Syria.) And all went to be taxed, every one into his own city. And Joseph also went up from Galilee, out of the city of Nazareth, into Judæa, unto the city of David, which is called Bethlehem; (because he was of the house and lineage of David:) To be taxed with Mary his espoused wife, being great with child.
There is described a secular registration, implied a spiritual, to be laid before the King not of earth but of Heaven; a registering of faith: a census of souls. For the old census of the Synagogue was abolished, a new census of the Church was preparing. And to decide that the census was not of Augustus, but of Christ, the whole world is ordered to be registered. For who could demand the registration of the whole world but He who had dominion over it, for the earth is not of Augustus, but the earth is the Lord’s? (Ps. 24:1.)