Ver. 4 sounds the depths in both its clauses. In the first the psalmist shuts out all other aspects of his guilt, and is absorbed in its solemnity as viewed in relation to God. It is asked, How could David have thought of his sin, which had in so many ways been "against" others, as having been "against Thee, Thee only"? As has been noted above, this confession has been taken to demonstrate conclusively the impossibility of the Davidic authorship. But surely it argues a strange ignorance of the language of a penitent soul, to suppose that such words as the psalmist's could be spoken only in regard to sins which had no bearing at all on other men. David's deed had been a crime against Bathsheba, against Uriah, against his family and his realm; but these were not its blackest characteristics. Every crime against man is sin against God. "Inasmuch as ye have done it unto one of the least of these ... ye have done it unto Me" is the spirit of the Decalogue as well as the language of Jesus. And it is only when considered as having relation to God that crimes are darkened into sins. The psalmist is stating a strictly true and profound thought when he declares that he has sinned "against Thee only." Further, that thought has, for the time being, filled his whole horizon. Other aspects of his shameful deed will torture him enough in coming days, even when he has fully entered into the blessedness of forgiveness; but they are not present to his mind now, when the one awful thought of his perverted relation to God swallows up all others. A man who has never felt that all-engrossing sense of his sin as against God only has much to learn.
The second clause of ver. 4 opens the question whether "in order that" is always used in the Old Testament in its full meaning as expressing intention, or sometimes in the looser signification of "so that," expressing result. Several passages usually referred to on this point (e.g., Psalm xxx. 12; Exod. xi. 9; Isa. xliv. 9; Hos. viii. 4) strongly favour the less stringent view, which is also in accordance with the genius of the Hebrew race, who were not metaphysicians. The other view, that the expression here means "in order that," insists on grammatical precision in the cries of a penitent heart, and clogs the words with difficulty. If their meaning is that the psalmist's sin was intended to show forth God's righteousness in judging, the intention must have been God's, not the sinner's; and such a thought not only ascribes man's sin directly to God, but is quite irrelevant to the psalmist's purpose in the words. For he is not palliating his transgression or throwing it on Divine predestination (as Cheyne takes him to be doing), but is submitting himself, in profoundest abasement of undivided guilt, to the just judgment of God. His prayer for forgiveness is accompanied with willingness to submit to chastisement, as all true desire for pardon is. He makes no excuses for his sin, but submits himself unconditionally to the just judgment of God. "Thou remainest the Holy One; I am the sinner; and therefore Thou mayest, with perfect justice, punish me and spurn me from Thy presence" (Stier).
Vv. 5, 6, are marked as closely related by the "Behold" at the beginning of each. The psalmist passes from penitent contemplation and confession of his acts of sin to acknowledge his sinful nature, derived from sinful parents. "Original sin" is theological terminology for the same facts which science gathers together under the name of "heredity." The psalmist is not responsible for later dogmatic developments of the idea, but he feels that he has to confess not only his acts but his nature. "A corrupt tree cannot bring forth good fruit." The taint is transmitted. No fact is more plain than this, as all the more serious observers of human life and of their own characters have recognised. Only a superficial view of humanity or an inadequate conception of morality can jauntily say that "all children are born good." Theologians have exaggerated and elaborated, as is their wont, and so have made the thought repugnant; but the derived sinful bias of human nature is a fact, not a dogma, and those who know it and their own share of it best will be disposed to agree with Browning, in finding one great reason for believing in Biblical religion, that—
"'Tis the faith that launched point-blank her dart
At the head of a lie—taught Original Sin,
The Corruption of Man's Heart."
The psalmist is not, strictly speaking, either extenuating or aggravating his sin by thus recognising his evil nature. He does not think that sin is the less his, because the tendency has been inherited. But he is spreading all his condition before God. In fact, he is not so much thinking of his criminality as of his desperate need. From a burden so heavy and so intertwined with himself none but God can deliver him. He cannot cleanse himself; for self is infected. He cannot find cleansing among men, for they too have inherited the poison. And so he is driven to God, or else must sink into despair. He who once sees into the black depths of his own heart will give up thereafter all ideas of "every man his own redeemer." That the psalmist's purpose was not to minimise his own guilt is clear, not only from the tone of the psalm, but from the antithesis presented by the Divine desire after inward truth in the next verse, which is out of place if this verse contains a palliation for sin.
We can scarcely miss the bearing of this verse on the question of whether the psalm is the confession of an individual penitent or that of the nation. It strongly favours the former view, though it does not make the latter absolutely impossible.
The discovery of inherent and inherited sinfulness brings with it another discovery—that of the penetrating depth of the requirements of God's law. He cannot be satisfied with outside conformity in deed. The more intensely conscience realises sin, the more solemnly rises before it the Divine ideal of man in its inwardness as well as in its sweep. Truth within—inward correspondence with His will, and absolute sincerity of soul are His desire. But I am "born in iniquity": a terrible antithesis, and hopeless but for one hope, which dawns over the suppliant like morning on a troubled sea. If we cannot ask God to make us what He wishes us to be, these two discoveries of our nature and of His will are open doorways to despair; but he who apprehends them wisely will find in their conjoint operation a force impelling him to prayer, and therefore to confidence. Only God can enable such a Being as man to become such as He will delight in; and since He seeks for truth within, He thereby pledges Himself to give the truth and wisdom for which He seeks.
Meditation on the sin which was ever before the psalmist, passes into renewed prayers for pardon, which partly reiterate those already offered in vv. 1, 2. The petition in ver. 7 for purging with hyssop alludes to sprinkling of lepers and unclean persons, and indicates both a consciousness of great impurity and a clear perception of the symbolic meaning of ritual cleansings. "Wash me" repeats a former petition; but now the psalmist can venture to dwell more on the thought of future purity than he could do then. The approaching answer begins to make its brightness visible through the gloom, and it seems possible to the suppliant that even his stained nature shall glisten like sunlit snow. Nor does that expectation exhaust his confidence. He hopes for "joy and gladness." His bones have been crushed—i.e., his whole self has been, as it were, ground to powder by the weight of God's hand; but restoration is possible. A penitent heart is not too bold when it asks for joy. There is no real well-founded gladness without the consciousness of Divine forgiveness. The psalmist closes his petitions for pardon (ver. 9) with asking God to "hide His face from his sins," so that they be, as it were, no more existent for Him, and, by a repetition of the initial petition in ver. 1, for the blotting out of "all mine iniquities."
The second principal division begins with ver. 10, and is a prayer for purity, followed by vows of glad service. The prayer is contained in three verses (10-12), of which the first implores complete renewal of nature, the second beseeches that there may be no break between the suppliant and God, and the third asks for the joy and willingness to serve which would flow from the granting of the desires preceding. In each verse the second clause has "spirit" for its leading word, and the middle one of the three asks for "Thy holy spirit." The petitions themselves, and the order in which they occur, are deeply significant, and deserve much more elucidation than can be given here. The same profound consciousness of inward corruption which spoke in the former part of the psalm shapes the prayer for renewal. Nothing less than a new creation will make this man's heart "clean." His past has taught him that. The word employed is always used of God's creative act; and the psalmist feels that nothing less than the power which brooded over the face of primeval chaos, and evolved thence an ordered world, can deal with the confused ruin within himself. What he felt that he must have is what prophets promised (Jer. xxiv. 7; Ezek. xxxvi. 26) and Christ has brought—a new creation, in which, while personality remains unaffected, and the components of character continue as before, a real new life is bestowed, which stamps new directions on affections, gives new aims, impulses, convictions, casts out inveterate evils, and gradually changes "all but the basis of the soul." A desire for pardon which does not unfold into such longing for deliverance from the misery of the old self is not the offspring of genuine penitence, but only of base fear.
"A steadfast spirit" is needful in order to keep a cleansed heart clean; and, on the other hand, when, by cleanness of heart, a man is freed from the perturbations of rebellious desires and the weakening influences of sin, his spirit will be steadfast. The two characteristics sustain each other. Consciousness of corruption dictated the former desire; penitent recognition of weakness and fluctuation inspires the latter. It may be observed, too, that the triad of petitions having reference to "spirit" has for its central one a prayer for God's Spirit, and that the other two may be regarded as dependent on that. Where God's Spirit dwells, the human spirit in which it abides will be firm with uncreated strength. His energy, being infused into a tremulous, changeful humanity, will make it stable. If we are to stand fast, we must be stayed on God.