12. Who can understand his errors? This exclamation shows us what use we should make of the promises of the law, which have a condition annexed to them. It is this: As soon as they come forth, every man should examine his own life, and compare not only his actions, but also his thoughts, with that perfect rule of righteousness which is laid down in the law. Thus it will come to pass, that all, from the least to the greatest, seeing themselves cut off from all hope of reward from the law, will be constrained to flee for refuge to the mercy of God. It is not enough to consider what the doctrine of the law contains; we must also look into ourselves, that we may see how far short we have come in our obedience to the law. Whenever the Papists hear this promise,

"He who doeth these things shall live in them,"
(Leviticus 18:5,)

they do not hesitate at once to connect eternal life with the merit of their works, as if it were in their own power to fulfill the law, of which we are all transgressors, not only in one point, but in all its parts. David, therefore, being involved as it were in a labyrinth on all sides, acknowledges with astonishment that he is overwhelmed under a sense of the multitude of his sins. We ought then to remember, in the first place, that as we are personally destitute of the righteousness which the law requires, we are on that account excluded from the hope of the reward which the law has promised; and, in the next place, that we are guilty before God, not of one fault or of two, but of sins innumerable, so that we ought, with the bitterest sorrow, to bewail our depravity, which not only deprives us of the blessing of God, but also turns to us life into death. This David did. There is no doubt that when, after having said that God liberally offers a reward to all who observe his law, he cried out, Who can understand his errors? it was from the terror with which he was stricken in thinking upon his sins. By the Hebrew word twaygs, shegioth, which we have translated errors, some think David intends lesser faults; but in my judgment he meant simply to say, that Satan has so many devices by which he deludes and blinds our minds, that there is not a man who knows the hundredth part of his own sins. The saints, it is true, often offend in lesser matters, through ignorance and inadvertence; but it happens also that, being entangled in the snares of Satan, they do not perceive even the grosser faults which they have committed. Accordingly, all the sins to the commission of which men give themselves loose reins, not being duly sensible of the evil which is in them, and being deceived by the allurements of the flesh, are justly included under the Hebrew word here used by David, which signifies faults or ignorances. ⁴ In summoning himself and others before the judgment-seat of God, he warns himself and them, that although their consciences do not condemn them, they are not on that account absolved; for God sees far more clearly than men's consciences, since even those who look most attentively into themselves, do not perceive a great part of the sins with which they are chargeable.

After making this confession, David adds a prayer for pardon, Cleanse thou me from my secret sins. The word cleanse is to be referred not to the blessing of regeneration, but to free forgiveness; for the Hebrew verb hqn, nakah, here used, comes from a word which signifies to be innocent. The Psalmist explains more clearly what he intended by the word errors, in now calling them secret sins; that is to say, those with respect to which men deceive themselves, by thinking that they are no sins, and who thus deceive themselves not only purposely and by expressly aiming at doing so, but because they do not enter into the due consideration of the majesty of the judgment of God. It is in vain to attempt to justify ourselves under the pretext and excuse of ignorance. Nor does it avail any thing to be blind as to our faults, since no man is a competent judge in his own cause. We must, therefore, never account ourselves to be pure and innocent until we are pronounced such by God's sentence of absolution or acquittal. The faults which we do not perceive must necessarily come under the review of God's judgment, and entail upon us condemnation, unless he blot them out and pardon them; and if so, how shall he escape and remain unpunished who, besides these, is chargeable with sins of which he knows himself to be guilty, and on account of which his own conscience compels him to judge and condemn himself? Farther, we should remember that we are not guilty of one offense only, but are overwhelmed with an immense mass of impurities. The more diligently any one examines himself, the more readily will he acknowledge with David, that if God should discover our secret faults, there would be found in us an abyss of sins so great as to have neither bottom nor shore, as we say; ⁵ for no man can comprehend in how many ways he is guilty before God. From this also it appears, that the Papists are bewitched, and chargeable with the grossest hypocrisy, when they pretend that they can easily and speedily gather all their sins once a year into a bundle. The decree of the Lateran Council commands every one to confess all his sins once every year, and at the same time declares that there is no hope of pardon but in complying with that decree. Accordingly, the blinded Papist, by going to the confessional, to mutter his sins into the ear of the priest, thinks he has done all that is required, as if he could count upon his fingers all the sins which he has committed during the course of the whole year; whereas, even the saints, by strictly examining themselves, can scarcely come to the knowledge of the hundredth part of their sins, and, therefore, with one voice unite with David in saying, Who can understand his errors? Nor will it do to allege that it is enough if each performs the duty of reckoning up his sins to the utmost of his ability. This does not diminish, in any degree, the absurdity of this famous decree. ⁶ As it is impossible for us to do what the law requires, all whose hearts are really and deeply imbued with the principle of the fear of God must necessarily be overwhelmed with despair, so long as they think themselves bound to enumerate all their sins, in order to their being pardoned; and those who imagine they can disburden themselves of their sins in this way must be persons altogether stupid. I know that some explain these words in a different sense, viewing them as a prayer, in which David beseeches God, by the guidance of his Holy Spirit, to recover him from all his errors. But, in my opinion, they are to be viewed rather as a prayer for forgiveness, and what follows in the next verse is a prayer for the aid of the Holy Spirit, and for success to overcome temptations.

13. Keep back thy servant also from presumptuous sins. By presumptuous sins he means known and evident transgressions, ⁷ accompanied with proud contempt and obstinacy. By the word keep back, he intimates, that such is the natural propensity of the flesh to sin, that even the saints themselves would immediately break forth or rush headlong into it, did not God, by his own guardianship and protection, keep them back. It is to be observed, that while he calls himself the servant of God, he nevertheless acknowledges that he had need of the bridle, lest he should arrogantly and rebelliously break forth in transgressing the law of God. Being regenerated by the Spirit of God, he groaned, it is true, under the burden of his sins; but he knew, on the other hand, how great is the rebellion of the flesh, and how much we are inclined to forgetfulness of God, from which proceed contempt of his majesty and all impiety. Now, if David, who had made so much progress in the fear of God, was not beyond the danger of transgressing, how shall the carnal and unrenewed man, in whom innumerable lusts exercise dominion, be able to restrain and govern himself by his own free will? Let us learn, then, even although the unruliness of our wayward flesh has been already subdued by the denial of ourselves, to walk in fear and trembling; for unless God restrain us, our hearts will violently boil with a proud and insolent contempt of God. This sense is confirmed by the reason added immediately after, that they may not have dominion over me. By these words he expressly declares, that unless God assist him, he will not only be unable to resist, but will be wholly brought under the dominion of the worst vices. This passage, therefore, teaches us not only that all mankind are naturally enslaved to sin, but that the faithful themselves would become the bond-slaves of sin also, if God did not unceasingly watch over them to guide them in the path of holiness, and to strengthen them for persevering in it. There is also another useful lesson which we have here to attend to, namely, that we ought never to pray for pardon, without, at the same time, asking to be strengthened and fortified by the power of God for the time to come, that temptations, in future, may not gain advantage over us. And although we may feel in our hearts the incitements of concupiscence goading and distressing us, we ought not, on that account, to become discouraged. The remedy to which we should have recourse is to pray to God to restrain us. No doubt, David could have wished to feel in his heart no stirrings of corruption; but knowing that he would never be wholly free from the remains of sin, until at death he had put off this corrupt nature, he prays to be armed with the grace of the Holy Spirit for the combat, that iniquity might not reign victorious over him. In the end of the verse there are two things to be observed. David, in affirming that he shall then be upright and clean from much wickedness, attributes, in the first place, the honor of preserving him innocent to the spiritual assistance of God; and depending upon it, he confidently assures himself of victory over all the armies of Satan. In the second place, he acknowledges, that unless he is assisted by God, he will be overwhelmed with an immense load, and plunged as it were into a boundless abyss of wickedness: for he says, that aided by God, he will be clear not of one fault or of two, but of many. From this it follows, that as soon as we are abandoned by the grace of God, there is no kind of sin in which Satan may not entangle us. Let this confession of David then quicken us to earnestness in prayer; for in the midst of so many and various snares, it does not become us to fall asleep or to be indolent. Again, let the other part of the Psalmist's exercise predominate in our hearts -- let us boast with him, that although Satan may assault us by many and strong armies, we will nevertheless be invincible, provided we have the aid of God, and will continue, in despite of every hostile attempt, to hold fast our integrity.

14. Let the words of my mouth, and the meditation of my heart. David asks still more expressly to be fortified by the grace of God, and thus enabled to live an upright and holy life. The substance of the verse is this: I beseech thee, O God, not only to keep me from breaking forth into the external acts of transgression, but also to frame my tongue and my heart to the obedience of thy law. We know how difficult it is, even for the most perfect, so to bridle their words and thoughts, as that nothing may pass through their heart or mouth which is contrary to the will of God; and yet this inward purity is what the law chiefly requires of us. Now, the rarer this virtue -- the rarer this strict control of the heart and of the tongue is, let us learn so much the more the necessity of our being governed by the Holy Spirit, in order to regulate our life uprightly and honestly. By the word acceptable, the Psalmist shows that the only rule of living well is for men to endeavor to please God, and to be approved of him. The concluding words, in which he calls God his strength and his redeemer, he employs to confirm himself in the assured confidence of obtaining his requests.