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."