6. But what Isaiah said, “From the height above, or from the depth beneath,” was meant to indicate, that “He who descended was the same also who ascended.” But in this that he said, “The Lord Himself shall give you a sign,” he declared an unlooked-for thing with regard to His generation, which could have been accomplished in no other way than by God the Lord of all, God Himself giving a sign in the house of David. For what great thing or what sign should have been in this, that a young woman conceiving by a man should bring forth,—a thing which happens to all women that produce offspring? But since an unlooked-for salvation was to be provided for men through the help of God, so also was the unlooked-for birth from a virgin accomplished; God giving this sign, but man not working it out.