6 But where thirsts our soul, and our flesh manifoldly, not for any one but for You, O Lord, that is our God? It thirsts where? “In a land desert, and without way, and without water.” Of this world we have spoken, the same is Idumæa, this is the desert of Idumæa, whence the Psalm has received its title. “In a land desert.” Too little it is to say “desert,” where no man dwells; it is besides, both “without way, and without water.” O that the same desert had even a way: O that into this a man running, even knew where he might thence get forth!...Evil is the desert, horrible, and to be feared: and nevertheless God has pitied us, and has made for us a way in the desert, Himself our Lord Jesus Christ: and has made for us a consolation in the desert, in sending to us preachers of His Word: and has given to us water in the desert, by fulfilling with the Holy Spirit His preachers, in order that there might be created in them a well of water springing up unto life everlasting. And, lo! We have here all things, but they are not of the desert....
7. “Thus in a holy thing I have appeared to You, that I might see Your power and Your glory”....Unless a man first thirst in that desert, that is in the evil wherein he is, he never arrives at the good, which is God. But “I have appeared to You,” he says, “in a holy thing.” Now in a holy thing is there great consolation. “I have appeared to You,” is what? In order that You might see me: and for this reason You have seen me, in order that I might see You. “I have appeared to You, that I might see.” He has not said, “I have appeared to You, that You might see:” but, “I have appeared to You, that I might see Your power and Your glory.” Whence also the Apostle, “But now,” he says, “knowing God, nay, having been known of God.” For first you have appeared to God, in order that to you God might be able to appear. “That I might see Your power and Your glory.” In truth in that forsaken place, that is, in that desert, if as though from the desert a man strives to obtain enough for his sustenance, he will never see the power of the Lord, and the glory of the Lord, but he will remain to die of thirst, and will find neither way, nor consolation, nor water, whereby he may endure in the desert. But when he shall have lifted up himself to God, so as to say to Him out of all his inward parts, “My soul has thirsted for You; how manifoldly for You also my flesh!” lest perchance even the things necessary for the flesh of others he ask, and not of God, or else long not for that resurrection of the flesh, which God has promised to us: when, I say, he shall have lifted up himself, he will have no small consolations.
8....But you have heard but now when the Gospel was being read in what terms He has notified His Majesty: “I and My Father are One.” Behold how great a Majesty and how great an Equality with the Father has come down to the flesh because of our infirmity. Behold how greatly beloved we have been, before that we loved God. If before that we loved God, so much by Him we were beloved, as that His Son, Equal with Himself, He made a Man for our sake, what does He reserve for us now loving Him? Therefore many men think it to be a very small thing that the Son of God has appeared on earth; because they are not in the Holy One, to them has not appeared the power of the Same and the glory of the Same: that is, not yet have they a heart made holy, whence they may perceive the eminence of that virtue, and may render thanks to God, nor that to which for their own sakes so great an One came, unto what a nativity, unto what a Passion, they are not able to see, His glory and His power.
9. “For better is Your mercy than lives.” Many are the lives of men, but one life God promises: and He gives not this to us as if for our merits but for His mercy....For what is so just a thing as that a sinner should be punished? Though a just thing it be that a sinner should be punished, it has belonged to the mercy of Him not to punish a sinner but to justify him, and of a sinner to make a just man, and of an ungodly man to make a godly man. Therefore “His mercy is better than lives.” What lives? Those which for themselves men have chosen. One has chosen for himself a life of business, another a country life, another a life of usury, another a military life; one this, another that. Divers are the lives, but “better is Your” life “than” our “lives.”...“My lips shall praise You.” My lips would not praise You, unless before me were to go Your mercy. By Your gift You I praise, through Your mercy You I praise. For I should not be able to praise God, unless He gave me to be able to praise Him.
10. “So I will speak good of You in my life, and in Your name I will lift up my hands”. Now in my life which to me You have given, not in that which I have chosen after the world with the rest among many lives, but that which You have given to me through Your mercy, that I should praise You. “So I will speak good of You in my life.” What is “so”? That to Your mercy I may ascribe my life wherein You I praise, not to my merits. “And in Your name I will lift up my hands.” Lift up therefore hands in prayer. Our Lord has lifted up for us His hands on the Cross, and stretched out were His hands for us, and therefore were His hands stretched out on the Cross, in order that our hands might be stretched out unto good works: because His Cross has brought us mercy. Behold, He has lifted up hands, and has offered for us Himself a Sacrifice to God, and through that Sacrifice have been effaced all our sins. Let us also lift up our hands to God in prayer: and our hands being lifted up to God shall not be confounded, if they be exercised in good works. For what does he that lifts up hands? Whence has it been commanded that with hands lifted up we should pray to God? For the Apostle says, “Lifting up pure hands without anger and dissension.” It is in order that when you lift up hands to God, there may come into your mind your works. For whereas those hands are lifted up that you may obtain that which you will, those same hands you think in good works to exercise, that they may not blush to be lifted up to God. “In your name I will lift up my hands.” Those are our prayers in this Idumæa, in this desert, in the land without water and without way, where for us Christ is the Way, but not the way of this earth.
11....Already our fathers are dead, but God lives: here we could not always have fathers, but there we shall always have one living Father, when we have our father-land....What sort of country is that? But you love here riches. God Himself shall be to you your riches. But you love a good fountain. What is more passing clear than that wisdom? What more bright? Whatsoever is an object of love here, in place of all you shall have Him that has made all things, “as though with marrow and fatness my soul should be filled: and lips of exultation shall praise Your name.” In this desert, in Your name I will lift up my hands: let my soul be filled as though with marrow and fatness, “and my lips with exultation shall praise Your name.” For now is prayer, so long as there is thirst: when thirst shall have passed away, there passes away praying and there succeeds praising. “And lips of exultation shall praise Your name.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)