3 But that there is a strengthening of the sense in repetition, by many passages of the Scriptures we are taught. Thence is that which the Lord says, “Verily, Verily.” Thence in certain Psalms is, “So be it, So be it.” To signify the thing, one “So be it” would have been sufficient: to signify confirmation, there has been added another “So be it.”...Countless passages of such sort there are throughout all the Scriptures. With these it is sufficient that we have commended to your notice a way of speaking which you may observe in all like cases: now to the substance attend: “We will confess to You,” he says, “and we will invoke.” I have said why before invocation confession does precede: because he whom you invoke, you invite. But he wills not to come when invoked, if you shall have been lifted up: lifted up if you shall have been, you will not be able to confess. And you deny not any things to God that He knows not. Therefore your confession does not teach Him, but it purges you.
4....Hear ye now the words of Christ. For these seemed not as it were to be His words, “We will confess to You, O God, we will confess to You, and will invoke Your name.” Now begins the discourse in the person of the Head. But whether Head speaks or whether members speak, Christ speaks: He speaks in the person of the Head, He speaks in the person of the Body. But what has been said? There shall be two in one flesh. “This is a great Sacrament:” “I,” he says, “speak in Christ and in the Church.” And He Himself in the Gospel, “Therefore no longer two, but one flesh.” For in order that you may know these in a manner to be two persons, and again one by the bond of marriage, as one He speaks in Isaiah, and says, “As upon a Bridegroom he has bound upon me a mitre, and as a Bride he has clothed me with an ornament.” A Bridegroom He has called Himself in the Head, a Bride in the Body. He is speaking therefore as One, let us hear Him, and in Him let us also speak. Let us be the members of Him, in order that this voice may possibly be ours also. “I will tell forth,” he says, “all Your marvellous things.” Christ is preaching Himself, He is preaching Himself even in His members now existing, in order that He may guide unto Him others, and they may draw near that were not, and may be united with those members of Him, through which members of Him the Gospel has been preached; and there may be made one Body under one Head, in one Spirit, in one Life.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)