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 sgy'vt, 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. [1] 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 nqh, 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; 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. 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.

Footnotes

1 - "Dont a bon droict toutes pechez ausquels les hommes se laschent la bride, pource qu'ils ne sentent pas abon escient le real qui y est, et sont deceus par les allechemens de la chair, sont nommez du mot Hebrie a duquel David use yci qui signifie Fautes ou Ignorances." -- Fr.

Who can understand his errors? - The word rendered errors is derived from a verb which means to wander, to go astray; then, to do wrong, to transgress. It refers here to wanderings, or departures from the law of God, and the question seems to have been asked in view of the purity, the strictness, and the extent of the law of God. In view of a law so pure, so holy, so strict in its demands, and so extended in its requirements - asserting jurisdiction over the thoughts, the words, and the whole life - who can recall the number of times that he has departed from such a law? A sentiment somewhat similar is found in Psalm 119:96, "I have seen an end of all perfection; thy commandment is exceeding broad." The language is such as every man who has any just sense of the nature and the requirements of the law, and a just view of his own life, must use in reference to himself. The reason why any man is elated with a conviction of his own goodness is that he has no just sense of the requirements of the law of God; and the more anyone studies that law, the more will he be convinced of the extent of his own depravity.
Hence, the importance of preaching the law, that sinners may be brought to conviction of sin; hence the importance of presenting it constantly before the mind of even the believer, that he may be kept from pride, and may walk humbly before God. And who is there that can understand his own errors? Who can number up the sins of a life? Who can make an estimate of the number of impure and unholy thoughts which, in the course of many years, have flitted through, or found a lodgment in the mind? Who can number up the words which have been spoken and should not have been spoken? Who can recall the forgotten sins and follies of a life - the sins of childhood, of youth, of riper years? There is but one Being in the universe that can do this. To Him all this is known. Nothing has escaped His observation; nothing has faded from His memory. Nothing can prevent His making a full disclosure of this if He shall choose to do so. It is in His power at any moment to overwhelm the soul with the recollection of all this guilt; it is in His power to cover us with confusion and shame at the revelation of the judgment-day. Our only hope - our only security - that He will not do this, is in His mercy; and that He may not do it, we should without delay seek His mercy, and pray that our sins may be so blotted out that they shall not be disclosed to us and to assembled worlds when we appear before Him.
Cleanse thou me from secret faults - The word here rendered secret means that which is hidden, covered, concealed. The reference is to those errors and faults which had been hidden from the eye of him who had committed them, as well as from the eye of the world. The sense is, that the law of God is so spiritual, and so pure, and so extended in its claims, that the author of the psalm felt that it must embrace many things which had been hidden even from his own view - errors and faults lying deep in the soul, and which had never been developed or expressed. From these, as well as from those sins which had been manifest to himself and to the world, he prayed that he might be cleansed. These are the things that pollute the soul; from these the soul must be cleansed, or it can never find permanent peace. A man who does not desire to be cleansed from all these "secret faults" cannot be a child of God; he who is a child of God will pray without ceasing that from these pollutions of the soul he may be made pure.

Who can understand his errors? - It is not possible, without much of the Divine light, to understand all our deviations from, not only the letter, but the spirituality, of the Divine law. Frequent self-examination, and walking in the light, are essentially necessary to the requisite degree of spiritual perfection.
Cleanse thou me from secret faults - From those which I have committed, and have forgotten; from those for which I have not repented; from those which have been committed in my heart, but have not been brought to act in my life; from those which I have committed without knowing that they were sins, sins of ignorance; and from those which I have committed in private, for which I should blush and be confounded were they to be made public.

Who can understand [his] (l) errors? cleanse thou me from secret [faults].
(l) Then there is no reward of duty, but of grace: for where sin is, there death is the reward.

Who can understand his errors?.... Sin is an error, a wandering out of the way of God, swerving from the rule of his word; and many mistakes are made by the people of God themselves; even so many that they cannot number them; they are more than the hairs of their head; they cannot understand, find out and express, neither their number, nor their evil nature, nor the many aggravating circumstances which attend them: this the psalmist said, upon a view of the large extent, glory, and excellency of the word of God; and upon comparing himself with it, in which, as in a glass, he saw how far short he came of it, and what a disagreement and want of conformity there was in him unto it; see Psalm 119:97; and he suggests, that though the word he had been describing was perfect, pure, and clean, he was not; nor could he expect any reward of debt, but merely of grace, for his observance of it; and that it was best, under a sense of sin, to have recourse, not to works of righteousness done by men; but to the grace and mercy of God in Christ, as follows:
cleanse thou me from secret faults; by which are meant not such sins as are done in secret, and are unknown to men; such as David's sin with Bathsheba, 2-Samuel 12:12; nor the inward motions of sin in the heart, to which none are privy but God, and a man's own soul; not but that each of these may be properly enough included in such a petition; but sins, which are unknown to a man himself are meant: there are some actions, which, though known when committed, are not known to be sinful ones; and there are some sins which are committed unadvisedly, and through carelessness, and pass unobserved; not only many vain and sinful thoughts pass to and fro uncontrolled, without being taken notice of; but many foolish and idle words are spoken, and many evil actions, through infirmity and inadvertency, are done, which, when a good man, at the close of a day, comes to reflect upon the things that have passed in it, are quite hidden from him, are unknown to him, being unobserved by him; wherefore such a petition is highly proper to be inserted in his address at the throne of grace: and which also supposes the person sensible of the defiling nature of sin, and of his own impotency to cleanse himself from it; and that God only can do it, who does it by the application of the blood of his Son, which cleanses from all sin; for this respects not regenerating and sanctifying grace, but pardoning grace; a manifestation of it, a view of acquittance from sin by Christ, and of freedom from obligation to punishment for it.

The clearer our view of the law, the more manifest are our sins. Still for its full effect we need divine grace to show us our faults, acquit us, restrain us from the practice, and free us from the power, of sin. Thus only can our conduct be blameless, and our words and thoughts acceptable to God.

Who - Thy law, O Lord, is holy and just and good. But I fall infinitely short of it. Cleanse - Both by justification, through the blood of thy son; and by sanctification thro' thy holy spirit. Though the first may seem to be principally intended, because he speaks of his past sins. Secret - From the guilt of such sins as were secret either, from others; such as none knows but God and my own conscience: or, from myself; such as I never observed, or did not discern the evil of. Pardon my unknown sins, of which I never repented particularly, as I should have done.