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.
This was then the first public enrolment of souls to the Lord, to Whom all enrol themselves not at the voice of the crier, but of the Prophet, who says, O clap your hands, all ye people. (Ps. 47:1.) But in order that men might know that it was an enrolment of righteousness, there came up to it Joseph andMary, the just man and the virgin. He who was to be guardian of the Word and she who was to bring it forth.