The words which follow, containing a prayer for the building up of Zion, and a prediction of the continuous offering of sacrifice, present some difficulty. They do not necessarily presuppose that Jerusalem is in ruins; for "build Thou the walls" would be no less appropriate a petition if the fortifications were unfinished (as we know they were in David's time) than if they had been broken down. Nor do the words contradict the view of sacrifice just given, for the use of the symbol and the conviction of its insufficiency co-existed, in fact, in every devout life, and may well be expressed side by side. But the transition from so intensely personal emotions to intercession for Zion seems almost too sudden even for a nature as wide and warm as David's. If the closing verses are his, we may, indeed, see in them the king re-awaking to a sense of his responsibilities, which he had so long neglected, first, in the selfishness of his heart, and then in the morbid self-absorption of his remorse; and the lesson may be a precious one that the first thought of a pardoned man should be for others. But there is much to be said, on the other hand, in favour of the conjecture that these verses are a later addition, probably after the return from captivity, when the walls of Zion were in ruins, and the altar of the temple had been long cold. If so, then our psalm, as it came from David's full heart, would be all of a piece--one great gush of penitence and faith, beginning with, "Have mercy upon me, O God," ending with the assurance of acceptance, and so remaining for all ages the chart of the thorny and yet blessed path that leads "from death unto life." In that aspect, what it does not contain is as noteworthy as what it does. Not one word asks for exemption from such penalties of his great fall as can be inflicted by a loving Father on a soul that lives in His love. He cries for pardon, but he gives his back to the smiters whom God may please to send.