The case of the thief and of David, and of our call in order to illustrate the grace of God.
For if we recall that thief who was by reason of a single confession admitted into paradise, 1050 we shall feel that he did not acquire such bliss by the merits of his life, but obtained it by the gift of a merciful God. Or if we bear in mind those two grievous and heinous sins of King David, blotted out by one word of penitence, 1051 we shall see that neither here were the merits of his works sufficient to obtain pardon for so great a sin, but that the grace of God superabounded, as, when the opportunity for true penitence was taken, He removed the whole weight of sins through the full confession of but one word. If we consider also the beginning of the call and salvation of mankind, in which, as the Apostle says, we are saved not of ourselves, nor of our works, but by the gift and grace of God, we can clearly see how the whole of perfection is “not of him that willeth nor of him that runneth, but of God that hath mercy,” who makes us victorious over our faults, without any merits of works and life on our part to outweigh them, or any effort of our will availing to scale the difficult heights of perfection, or to subdue the flesh which we have to use: since no tortures of this body, and no contrition of heart, can be sufficient for the acquisition of that true chastity of the inner man so as to be able to gain that great virtue of purity (which is innate in the angels alone and indigenous as it were to heaven) merely by human efforts, i.e., without the aid of God: for the performance of everything good flows from His grace, who by multiplying His bounty has granted such lasting bliss, and vast glory to our feeble will and short and petty course of life.
Cf. S. Luke xxiii. 40.283:1051
Cf. 2 Sam. xii. 13.