At the time of his birth Christ, through whom every place was created, finds no place in the inn; and he who is Lord of all the world is born as though a foreigner, to enable us to be citizens whose homeland is heaven. He is wrapped in swaddling clothes in order to restore in his own Body the unity of the human race that had been rent asunder, and bring to the kingdom of heaven the garment of immortality whole and entire, resplendent with the purple color of his blood. He is born, brothers, in order to improve the very nature which the first human being had corrupted. He lies in swaddling clothes, but he reigns in heaven; he rests humbly in a cradle, but he thunders amid the clouds; he is placed in a manger, because it is evident that “all flesh is grass,” as Isaiah says. This is the grass, brothers, whose blossom is transformed into heavenly Bread, and by feasting on it we reach life eternal.
St. Peter Chrysologus, Sermon 140B, “On the Birth of the Lord”
Locus Communis 