1 The days have come for us to sing Allelujah....Now these days come only to pass away, and pass away to come, again, and typify the day which does not come and pass away, because it is neither preceded by yesterday to cause it to come, nor pressed upon by the morrow to cause it to pass....For as these days succeed in regular season, with a joyful cheerfulness, the past days of Lent, whereby the misery of this life before the Resurrection of the Lord's body is signified; so that day which after the Resurrection shall be given to the full body of the Lord, that is, to the holy Church, when all the troubles and sorrows of this life have been shut out, shall succeed with perpetual bliss. But this life demands from us self-restraint, that although groaning and weighed down with our toil and struggles, and desiring to be clothed upon with our house which is from heaven, we may refrain from secular pleasures: and this is signified by the number of forty, which was the period of the fasts of Moses, and Elias, and our Lord Himself....But by the number fifty after our Lord's resurrection, during which season we sing Allelujah, not the term and passing away of a certain season is signified, but that blessed eternity; because the denary added to forty signifies the reward paid to the faithful who toil in this life, which our Father has prepared an equal share of for the first and for the last. Let us therefore hear the heart of the people of God full of divine praises. He represents in this Psalm some one exulting in happy joyfulness, he prefigures the people whose hearts are overflowing with the love of God, that is, the body of Christ, freed from all evil.
2. “I will make confession unto You, O Lord,” he says, “with my whole heart”. Confession is not always confession of sins, but the praise of God is poured forth in the devotion of confession. The former mourns, the latter rejoices: the former shows the wound to the physician, the latter gives thanks for health. The latter confession signifies some one, not merely freed from every evil, but even separate from all the ill-disposed. And for this reason let us consider the place where he confesses unto the Lord with all his heart. “In the counsel,” he says, “of the upright, and in the congregation:” I suppose, of those who shall “sit upon the twelve thrones, judging the twelve tribes of Israel.” For there will be no longer an unjust man among them, the thefts of no Judas are allowed, no Simon Magus is baptized, wishing to buy the Spirit, while he designs to sell it; no coppersmith like Alexander does many evil deeds, no man covered with sheep's clothing creeps in with feigned fraternity; such as those among whom the Church must now groan, and such as she must then shut out, when all the righteous shall be gathered together.
“These are the great works of the Lord, sought out unto all His wills”: through which mercy forsakes none who confesses, no man's wickedness is unpunished....Let man choose for himself what he lists: the works of the Lord are not so constituted, that the creature, having free discretion allowed him, should transcend the will of the Creator, even though he act contrary to His will. God wills not that you should sin; for He forbids it: yet if you have sinned, imagine not that the man has done what he willed, and that has happened to God which He willed not. For as He would that man would not sin, so would He spare the sinner, that he may return and live; He so wills finally to punish him who persists in his sin, that the rebellious cannot escape the power of justice. Thus whatever choice you have made, the Almighty will not be at a loss to fulfil His will concerning you.
3. “Confession and glorious deeds are His work”. What is a more glorious deed than to justify the ungodly? But perhaps the work of man prevents that glorious work of God, so that when he has confessed his sins, he deserves to be justified....This is the glorious work of the Lord: for he loves most, to whom most is forgiven. This is the glorious work of the Lord: for “where sin abounded, there did grace much more abound.” But perhaps a man would deserve justification from works. “Not,” says he, “of works, lest any man boast. For we are His workmanship, created in Christ Jesus unto good works.” For a man works not righteousness save he be justified: but by “believing on Him that justifies the ungodly,” he begins with faith; that good may not by preceding show what he has deserved, but by following what he has received....
4. “He has made His wonderful works to be remembered”: by abasing this man, exalting that. Reserving unusual miracles for a fit season, that thus human weakness, intent upon novelty, may remember them, although His daily miracles be greater. He created so many trees throughout the whole earth, and no one wonders: He dried up one with a word, and the hearts of mortals were thunderstruck. For that miracle, which has not through its frequency become common, will cling most firmly to the heart. But of what use were the miracles, save that He might be feared? What too would fear profit, unless “the gracious and merciful Lord” gave “meat unto them that fear Him”?; meat that does not spoil, “bread that comes down from heaven,” which He gave to no deservings of ours. For “Christ died for the ungodly.” No one then would give such food, save a gracious and merciful Lord. But if He gave so much to this life, if the sinner who was to be justified received the Word made flesh; what shall he receive when glorified in a future world? For, “He shall ever be mindful of His covenant.” Nor has He who has given a pledge, given the whole.
5. “He shall show His people the power of His works”. Let not the holy Israelites, who have left all their possessions and have followed Him, be saddened; let them not be sorrowful and say, “Who then can be saved?” For “it is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.” For “with men these things are impossible, but with God all things are possible.” “That He may give them the heritage of the heathen.” For they went to the heathen, and enjoined the rich of this world “not to be high-minded, nor to trust in uncertain riches, but in the living God,” to whom that is easy which is difficult for men. For thus many were called, thus the heritage of the heathen has been occupied, thus it has happened, that even many who have not abandoned all their possessions in this life in order to follow Him, have despised even life itself for the sake of confessing His Name; and like camels humbling themselves to bear the burden of troubles, have entered as it were through a needle's eye, through the piercing straits of suffering. He has wrought these effects, unto whom all things are possible.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)