The psalmist begins abruptly with an exclamation (Oh, the blessedness, etc.). His new joy wells up irrepressibly. To think that he who had gone so far down in the mire, and had locked his lips in silence for so long, should find himself so blessed! Joy so exuberant cannot content itself with one statement of its grounds. It runs over in synonyms for sin and its forgiveness, which are not feeble tautology. The heart is too full to be emptied at one outpouring, and though all the clauses describe the same things, they do so with differences. This is true with regard to the words both for sin and for pardon. The three designations of the former present three aspects of its hideousness. The first, rendered ("transgression,") conceives of it as rebellion against rightful authority, not merely breach of an impersonal law, but breaking away from a rightful king. The second ("sin") describes it as missing a mark. What is in regard to God rebellion is in regard to myself missing the aim, whether that aim be considered as that which a man is, by his very make and relations, intended to be and do, or as that which he proposes to himself by his act. All sin tragically fails to hit the mark in both these senses. It is a failure as to reaching the ideal of conduct, "the chief end of man," and not less so as to winning the satisfaction sought by the deed. It keeps the word of promise to the ear, and breaks it to the hope, ever luring by lying offers; and if it gives the poor delights which it holds out, it ever adds something that embitters them, like spirits of wine methylated and made undrinkable. It is always a blunder to do wrong. The last synonym ("iniquity") means crookedness or distortion, and seems to embody the same idea as our words "right" and "wrong," namely the contrast between the straight line of duty and the contorted lines drawn by sinful hands. What runs parallel with law is right; what diverges is wrong. The three expressions for pardon are also eloquent in their variety. The first word means taken away or lifted off, as a burden from aching shoulders. It implies more than holding back penal consequences; it is the removal of sin itself, and that not merely in the multitudinousness of its manifestations in act, but in the depth of its inward source. This is the metaphor which Bunyan has made so familiar by his picture of the pilgrim losing his load at the cross. The second ("covered") paints pardon as God's shrouding the foul thing from His pure eyes, so that His action is no longer determined by its existence. The third describes forgiveness as God's not reckoning a man's sin to him, in which expression hovers some allusion to cancelling a debt. The clause "in whose spirit is no guile" is best taken as a conditional one, pointing to sincerity which confesses guilt as a condition of pardon. But the alternative construction as a continuation of the description of the forgiven man is quite possible; and if thus understood, the crowning blessing of pardon is set forth as being the liberation of the forgiven spirit from all "guile" or evil. God's kiss of forgiveness sucks the poison from the wound.
Retrospect of the dismal depth from which it has climbed is natural to a soul sunning itself on high. Therefore on the overflowing description of present blessedness follows a shuddering glance downwards to past unrest. Sullen silence caused the one; frank acknowledgment brought the other. He who will not speak his sin to God has to groan. A dumb conscience often makes a loud-voiced pain. This man's sin had indeed missed its aim; for it had brought about three things: rotting bones (which may be but a strong metaphor or may be a physical fact), the consciousness of God's displeasure dimly felt as if a great hand were pressing him down, and the drying up of the sap of his life, as if the fierce heat of summer had burned the marrow in his bones. These were the fruits of pleasant sin, and by reason of them many a moan broke from his locked lips. Stolid indifference may delay remorse, but its serpent fang strikes soon or later, and then strength and joy die. The Selah indicates a swell or prolongation of the accompaniment, to emphasise this terrible picture of a soul gnawing itself.