Glossa Ordinaria
Catena Aurea · Matthäusevangelium 1
Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, Behold, a Virgin shall be with child, and shall bring forth a Son, and they shall call His Name Emmanuel, which being interpreted is, God with us. Here we must enquire why he should say all this was done, when above he has only related the conception. It should be known that he says this to shew, that in the presence of God all this was done before it was done among men. Or he says, all this was done, because he is relating past events; for when he wrote, it was all done.
(non occ.) Or it may be said, that the word that does not here denote the cause; for the prophecy was not fulfilled merely because it was to be fulfilled. But it is put consecutively, as in Genesis, He hung the other on the gallows, that the truth of the interpreter might be proved; (Gen. 40:22.) since by the weighing of one, truth is established. So also in this place we must understand it as if it were, that which was foretold being done, the prophecy was accomplished.