Church Fathers on Matthew 1:23

It is the custom of the Evangelist to confirm what he says out of the Old Testament, for the sake of those Jews who believed on Christ, that they might recognize as fulfilled in the grace of the Gospel, the things that were foretold in the Old Testament; therefore he adds, 'Now all this was done.'

Or, he says, 'all this was done,' meaning, the Virgin was betrothed, she was kept chaste, she was found with child, the revelation was made by the Angel, that it might be fulfilled which was spoken. For that the Virgin should conceive and should bring forth would never have been fulfilled, had she not been espoused that she should not be stoned; and had not her secret been disclosed by the Angel, and so Joseph taken her unto him, that she was not dismissed to disgrace and to…

Otherwise; the Angel seeing the depths of the Divine mercy, the laws of nature broken through and reconciliation made, He who was above all made lower than all; all these wonders, all this he comprises in that one saying, 'Now all this hath happened;' as though he had said, Do not suppose that this is newly devised of God, it was determined of old. And he rightly cites the Prophet not to the Virgin, who as a maiden was untaught in such things, but to Joseph, as to one much…