Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
All Commentaries on Isaiah 7:14 Go To Isaiah 7
Augustine of Hippo
AD 430
Do you hesitate or refuse to believe his birth of a virgin, when you ought rather to believe that thus it was fitting for God to be born man? Learn that this, too, was foretold by the prophet: “Behold, a virgin shall conceive and bear a son, and his name shall be called Emmanuel, which is interpreted, God with us.” You will not doubt, therefore, the motherhood of a virgin if you want to believe the nativity of a God who does not relinquish the government of the universe and comes in flesh among human beings; who bestows fecundity on his mother yet does not diminish her integrity.