Thomas Aquinas, on Ps 50:1

“Unto the end, a psalm of David,”

“In the preceding Psalms of this decade, the Psalmist seems to have treated of those things that pertain to the state of the kingdom, whose glory he described and to which he invited others. But now, because the glory of this kingdom has been impeded by sin, he treats of the abolition of sin. Here two things must be considered. First, that in the order of the Psalms, this Psalm is the fiftieth, and this is the jubilee number, as is said in Lev. 27, in which the remission of all debts was made. Hence this number is fitting for this Psalm, in which he treats of the full remission of sins. Similarly, as regards the penitential Psalms, this one is placed fourth, and fittingly so: for the first pertains to contrition of heart; hence it says, Ps. 6: "Every night I will wash," etc. The second pertains to confession of mouth, Ps. 31: "I said, I will confess," etc. The third pertains to satisfaction; hence it says, Ps. 37: "I am afflicted," etc. But this fourth pertains to the effect of penance. In it is shown how penance restores a person to perfection; and therefore, among all the others, this Psalm is most frequently used in the Church, because this one solely implores mercy, and thus obtains pardon; and this is easy and can be fitting for anyone. In the other six penitential Psalms, there are certain heavy things, such as Ps. 6: "Every night I will wash my bed." And Ps. 101: "I ate ashes like bread," etc., which cannot be fitting for everyone. The title is as follows: "A Psalm of David, when Nathan the prophet came to him after he had gone in to Bathsheba." This history is expressly found in 2 Sam. 11 and 12, when David was in prosperity, saw a woman washing herself, and desired her, and committed adultery, and had her husband killed. And this displeased God, and Nathan the prophet was sent to him and brought him to the detestation of his sin under the likeness of a lost sheep. And David said, "I have sinned against the Lord." And his sin was forgiven. And this is the subject matter of this Psalm, namely the forgiveness of sin. But it should be known regarding the title of this Psalm that David in other Psalms speaks about others -- as in Ps. 21, "O God, my God," he speaks foretelling the Passion of Christ; and so in various Psalms he speaks about various things -- but this Psalm he composed for his own sake. In it he shows the guilt he committed, made manifest to the world, and similarly the pardon; and thus is fulfilled what the Lord said, 2 Sam. 12: "You did this in secret, and I will make it manifest." The reason for this manifestation is the divine mercy; for this manifestation is useful to the just, so that they may not presume on their own justice, because if David, after so many victories, after the gift of the Holy Spirit, after such great familiarity with God and prophecy, sinned, how much more should we, who are fragile and sinners, be on guard? 1 Cor. 10: "Let him who thinks he stands take heed lest he fall." Also, it is useful to sinners, so that they may not despair. Prov. 24: "If you despair, having fallen, in the day of anguish your strength will be diminished"; for David, after homicide and adultery, recovered the grace of prophecy. The manner of speaking in the title should be noted: "when he came" -- here he designates the pardon, which is treated in the Psalm, because through Nathan the Lord heard him and transferred his sin. But when it says, "when he went in to Bathsheba," the guilt is designated. Here two things are shown. First, that he names the guilt when he says, "and he went in." Ps. 11: "The words of the Lord are chaste words." Also, though he had committed two sins, namely adultery and homicide, Scripture named only the adultery. And this for two reasons. First, to designate that in scrutinizing and publicizing the sins of others, we should not be ready but very sparing. Prov. 24: "Do not lie in wait to seek wickedness in the house of the just"; and this is signified in Mt. 25, where the Lord enumerates the merits of the good diligently but passes over the demerits of the wicked. Also, it should be noted that when someone commits two sins and one is done for the sake of the other, one passes into the species of the other; just as one who commits theft in order to fornicate is called a fornicator rather than a thief. Now this Psalm is divided into two parts. First, he implores mercy; second, he promises amendment, at "I will teach the unjust." Regarding the first, he does two things. First, he asks for the relaxation of guilt; second, he asks for the restoration of holiness and grace, at "because my iniquity." He therefore first asks for the mercy of God, when he says, "Have mercy on me, O God." Here it should be known that, as is said in Prov. 14, "Sin makes peoples wretched." For just as one is not truly happy who abounds in riches, enjoys pleasures, and excels in honors, but rather one who enjoys God, so one is not wretched who is poor, miserable, weak, and infirm, but rather one who is a sinner. And therefore this man, who is a sinner, says, "Have mercy on me, O God," you who have mercy on all and hate nothing of what you have made, Wis. 11. And according to the apostle, "have mercy on whom you will," Rom. 9: "I will have mercy on whom I will." Therefore, if it is subject to your will to have mercy, "have mercy on me," namely a sinner. He does not wish to contend, he does not seek to argue, but takes the short way: "have mercy." Also, he does not allege a cause for mercy, not the services he rendered to God, not the dangers he endured for him, but implores only the mercy of God; hence he says, "according to your great mercy." Dan. 9: "Not in our justifications do we prostrate our prayers before your face, but in your many mercies." And it should be noted that one can hope for divine mercy for a double reason. One reason is from the consideration of the divine nature; the other reason is from the consideration of the multitude of its effects. First, therefore, he shows that he hopes for the mercy of God from the consideration of the divine nature, because it is proper to the divine nature that it is goodness itself. Hence Dionysius says that God is the very substance of goodness. And Boethius in his work On the Trinity says the same. Hence this mercy of God is nothing other than goodness directed toward dispelling wretchedness. Therefore, when I consider that it is proper to goodness to dispel wretchedness, and that God is goodness itself, I confidently have recourse to mercy. And it is called great in its incomprehensibility, by which it fills all things. Ps. 32: "The earth is full of the mercy of the Lord." And it has a place in all things: for the just have preserved their innocence on account of the mercy of God. Augustine: "Lord, I attribute to your grace the evils I have not committed." Also, sinners have been converted to justice on account of the mercy of God. 1 Tim. 1: "I have obtained mercy." Also, those existing in sin have experienced the mercy of God. Lam. 3: "The mercies of the Lord are many; for we are not consumed." Also, it is called great in its sublimity, because "his mercies are above all his works"; for mercy does not signify in God a passion of the soul, but goodness directed toward dispelling wretchedness. Also great in its duration. Is. 54: "With everlasting mercy I have had compassion on you." Also great in its power, because it made God become man, brought God from heaven to earth, and made the immortal one die. Eph. 2: "But God, who is rich in mercy." Also great in its effect, because from every wretchedness a person can be raised through mercy. Ps. 85: "Your mercy is great upon me, and you have forgiven the wickedness of my sin" (Ps. 31). And therefore I confidently ask: "Have mercy on me, O God." The other reason is that in all things from the beginning of the world I have found the effects of your mercy. And therefore he says, "and according to the multitude of your mercies, blot out my iniquity"; as if to say: have mercy on me, according as you have had mercy in many ways and on diverse people. Hence Is. 63 says: "I will be mindful of the mercies of the Lord." Ps. 24: "Remember your mercies," etc. "Blot out my iniquity." Here he sets forth the effect of having mercy. Nathan said, 2 Sam. 12: "The Lord has taken away your sin," etc. And so he was secure about pardon; but he wished the sin to be totally eradicated. Now a twofold effect of sin remains: namely, the debt of punishment and the stain on the soul. First, therefore, he asks for the removal of the debt of punishment; and therefore, "wash me yet more from my iniquity." It should be known that in Jer. 17 it is said that the sin of Judah was written with an iron pen, with a point of diamond; in the likeness of a judge who writes the offense, which is preserved written for as long as he has the intention of punishing; but if he puts aside this intention, he does not preserve the record. And so it is said to be written with a diamond pen when the sin is not blotted out. And this is what he says, "blot out my iniquity," that is, do not impute my iniquity to me for punishment. Is. 43: "I am he who blots out your iniquities." Also, ibid. 44: "I have blotted out your iniquities like a cloud, and your sins like a mist."”

Imported from an open dataset — not yet checked against the printed edition.