Vv. 3, 4, are the second stage. A dark fear shadows the singer's soul, and is swept away by a joyful assurance. The word rendered above "mark" is literally _keep_ or _watch_, as in ver. 6, and here seems to mean to _take account of_, or _retain_ in remembrance, in order to punish. If God should take man's sin into account in His dispositions and dealings, "O Lord, who shall stand?" No man could sustain that righteous judgment. He must go down before it like a flimsy hut before a whirlwind, or a weak enemy before a fierce charge. That thought comes to the psalmist like a blast of icy air from the north, and threatens to chill his hope to death and to blow his cry back into his throat. But its very hypothetical form holds a negation concealed in it. Such an implied negative is needed in order to explain the "for" of ver. 4. The singer springs, as it were, to that confidence by a rebound from the other darker thought. We must have tremblingly entertained the contrary dread possibility, before we can experience the relief and gladness of its counter-truth. The word rendered "forgiveness" is a late form, being found only in two other late passages (Neh. ix. 17; Dan. ix. 9). It literally means _cutting off_, and so suggests the merciful surgery by which the cancerous tumour is taken out of the soul. Such forgiveness is "with God," inherent in His nature. And that forgiveness lies at the root of true godliness. No man reverences, loves, and draws near to God so rapturously and so humbly as he who has made experience of His pardoning mercy, lifting a soul from its abysses of sin and misery. Therefore the psalmist, taught by what pardon has done for him in drawing him lovingly near to God, declares that its great purpose is "that Thou mayest be feared," and that not only by the recipient, but by beholders. Strangely enough, many commentators have found a difficulty in this idea, which seems sun-clear to those whose own history explains it to them. Grätz, for instance, calls it "completely unintelligible." It has been very intelligible to many a penitent who has been by pardon transformed into a reverent lover of God.