From the Homilies on the Book of St Matthew by St John Chrysostom (#1)
from Homily 5:
For he doth not call the saying Isaiah’s, but that of the God of all things. For this cause he said not, “that it might be fulfilled which was spoken of Isaiah,” but “which was spoken of the Lord.” For the mouth indeed was Isaiah’s, but the oracle was wafted from above.
What then saith this oracle? “Behold, a virgin shall be with child, and shall bring forth a son, and they shall call His name Emmanuel.”
How was it then, one may say, that His name was not called Emmanuel, but Jesus Christ? Because he said not, “thou shalt call,” but “they shall call,” that is, the multitude, and the issue of events. For here he puts the event as a name: and this is customary in Scripture, to substitute the events that take place for names.
Therefore, to say, “they shall call” Him “Emmanuel,” means nothing else than that they shall see God amongst men. For He hath indeed always been amongst men, but never so manifestly.