26 But this was discipline; admonition, not desertion. Lastly, giving thanks, he says what? “And being turned You have made me alive, and from the bottomless places of the earth again You have brought me back.” But when before? What is this “again”? You have fallen from a high place, O man, disobedient slave, O thou proud against your Lord, you have fallen. There hast come to pass in you, “every one that exalts himself shall be humbled:” may there come to pass in you, “every one that humbles himself shall be exalted.” Return thou from the deep. I return, he says, I return, I acknowledge; “O God, who is like You? How great troubles have You shown to me, many and evil! And being turned You have made me alive, and from the bottomless places of the earth again You have brought me back.” “We perceive,” I hear. You have brought us back from the bottomless places of the earth, hast brought us back from the depth and drowning of sin. But why “again”? When had it already been done? Let us go on, if perchance the latter parts of the Psalm itself do not explain to us the thing which here we do not yet perceive, namely, why he has said “again.” Therefore let us hear: “How great troubles You have shown to me, many and evil! And being turned You have made me alive, and from the bottomless places of the earth again You have brought me back.” What then? “You have multiplied Your righteousness, and being turned You have comforted me, and from the bottomless places of the earth again You have brought me back”. Behold a second “again”! If we labour to unravel this “again” when written once, who will be able to unravel it when doubled? Now “again” itself is a redoubling, and once more there is written “again.” May He be with us from whom is grace, may there be with us the arm also which we are telling forth to every generation that is to come: may He be with us Himself, and as with the key of His Cross open to us the mystery that is locked up. For it was not to no purpose that when He was crucified the veil of the temple was rent in the midst, but to show that through His Passion the secret things of all mysteries were opened. May He then Himself be with men passing over unto Him, be the veil taken away: may our Lord and Saviour Jesus Christ tell us why such a voice of the Prophet has been sent before, “You have shown to me troubles many and evil: and being turned You have made me alive, and from the bottomless places of the earth again You have brought me back.” Behold this is the first “again” which has been written. Let us see what this is, and we shall see why there is a second “again.”
27....Therein Christ died, wherein you are to die: and therein Christ rose again, wherein you are to rise again. By His example He taught you what you should not fear, for what you should hope. You feared death, He died: you despaired of rising again, He rose again. But you say to me, He rose again, do I by any means rise again? But He rose again in that which for you He received of you. Therefore your nature in Him has preceded you; and that which was taken of you, has gone up before you: therein therefore thou also hast ascended. Therefore He ascended first, and we in Him: because that flesh is of the human race....Behold one “again.” Hear of its being fulfilled from the Apostle: “If then you have risen with Christ, the things which are above seek ye, where Christ is sitting on the right hand of God; the things which are above mind ye, not the things which are upon the earth.” He then has gone before: already we also have risen again, but still in hope. Hear the Apostle Paul saying this same thing: “Even we ourselves groan in ourselves, looking for the adoption, the redemption of our body.” What is it then that Christ has granted to you? Hear that which follows: “For by hope we are saved: but hope which is seen is not hope. For that which a man sees, why does he hope for? But if that which we see not we hope for, through patience we wait for it.” We have been brought back therefore again from the bottomless places in hope. Why again? Because already Christ had gone before. But because we shall rise again in substance, for now in hope we are living, now after faith we are walking; we have been brought back from the bottomless places of the earth, by believing in Him who before us has risen again from the bottomless place of the earth....You have heard one “again,” you have heard the other: “again;” one “again” because of Christ going before; and the other, yet however in hope, and a thing which remains to be in substance. “You have multiplied Your righteousness,” already in me believing, already in those that first have risen again in hope....“You have multiplied Your righteousness, and being turned You have comforted me:” and because of the body to rise again at the end, even from the bottomless places of the earth again You have brought me back.
28. “For I will confess to You in the vessels of a Psalm Your truth”. The vessels of a Psalm are a Psaltery. But what is a Psaltery? An instrument of wood and strings. What does it signify? There is some difference between it and a harp:...there seems to be signified by the Psaltery the Spirit, by the harp the flesh. And because he had spoken of two bringings back of ours from the bottomless places of the earth, one after the Spirit in hope, the other after the body in substance; hear thou of these two: “For I will confess to You in the vessels of a Psalm Your truth.” This after the Spirit: concerning the body what? “I will psalm to You on a harp, Holy One of Israel.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)