John Calvin, Institutes of the Christian Religion, III.16.4
Our doctrine is, that justification is a thing of such value, that it cannot be put into the balance with any good quality of ours; and, therefore, could never be obtained unless it were gratuitous: moreover, that it is gratuitous to us, but not also to Christ, who paid so dearly for it; namely his own most sacred blood, out of which there was no price of sufficient value to pay what was due to the justice of God. When men are thus taught they are reminded that it is owing to no merit of theirs that the shedding of that most sacred blood is not repeated every time they sin. Moreover, we say that our pollution is so great, that it can never be washed away save in the fountain of his pure blood. Must not those who are thus addressed conceive a greater horror of sin than if it were said to be wiped off by a sprinkling of good works? If they have any reverence for God, how can they, after being once purified, avoid shuddering at the thought of again wallowing in the mire, and as much as in them lies troubling and polluting the purity of this fountain? �I have washed my feet,� (says the believing soul in the Song of Solomon, 5:3,) �how shall I defile them?� It is now plain which of the two makes the forgiveness of sins of less value, and derogates from the dignity of justification. They pretend that God is appeased by their frivolous satisfactions; in other words, by mere dross. We maintain that the guilt of sin is too heinous to be so frivolously expiated; that the offense is too grave to be forgiven to such valueless satisfactions; and, therefore, that forgiveness is the prerogative of Christ�s blood alone. They say that righteousness, wherever it is defective, is renewed and repaired by works of satisfaction. We think it too precious to be balanced by any compensation of works, and, therefore, in order to restore it, recourse must be had solely to the mercy of God.
