To prove that we have attained the hope of salvation by his grace alone, not by works [cf. Eph. 2:8–9], he states that “we are his creatures, since we have been reborn in Christ Jesus for good works, which God prepared beforehand that we should walk in them” [Eph. 2:10, cf. Vg.]. It is as if he said: Who of us can boast that he has appealed to God by his own righteousness when our first capacity for well-doing flows from regeneration? For, as we have by nature been created, oil will sooner be pressed from a stone than any good work from us. It is truly wonderful that man, condemned to such disgrace, dares still assume that he has anything left. Let us therefore admit, with this very great instrument of God, that the Lord “called us with a holy calling, not according to our works, but according to his purpose and … grace” [2 Tim. 1:9 p.], and that “the generosity and love of God our Savior was manifested toward us, for he saved us, not because of deeds done by us in righteousness, but on account of his own mercy, … that we might be justified by his grace and be made heirs of eternal life” [Titus 3:4–5, 7 p.]. By this confession we deprive man of all righteousness, even to the slightest particle, until, by mercy alone, he is reborn into the hope of eternal life, since if the righteousness of works brings anything to justify us, we are falsely said to be justified by grace. Obviously, the apostle was not forgetful when he declared justification free, since he proves in another passage that grace would no longer be grace if works availed [Rom. 11:6]. And what else does the Lord mean when he says that he “came not to call the righteous but sinners” [Matt. 9:13]? If only sinners are admitted, why do we seek entry through feigned righteousness?

—John Calvin
Institutes, 3.14.5.