Ambrose of Milan

This means, “Not I, who once ate from the earth [like Adam]. Not I who was once grass, as all flesh is grass, but Christ who lives in me. That is, there lives that living bread which comes from heaven, there lives wisdom, there lives righteousness, there lives the resurrection.”

He says “his Son,” not one of many, not “a Son” but his own. When he says “his own” he confirms that he has the property of eternal generation. This is the one whom he subsequently declares to have been born from a woman, so as to ascribe the fact of being born not to the Godhead but to the assumed body. He was made from a woman by assuming flesh and made under the law by observing the law. But that heavenly birth of his is prior to the law, while the incarnation happens later.