Vocatione Gentium, and elsewhere, teaches to like effect. For
in his De Vocatione Gentium he says as follows: Redemption by
the blood of Christ would become of little value, neither
would the preeminence of man's works be superseded by the
mercy of God, if justification, which is wrought through
grace, were due to the merits going before, so as to be, not
the free gift of a donor, but the reward due to the laborer.

But, although this doctrine is despised by the inexperienced,
nevertheless God-fearing and anxious consciences find by
experience that it brings the greatest consolation, because
consciences cannot be set at rest through any works, but only
by faith, when they take the sure ground that for Christ's
sake they have a reconciled God. As Paul teaches Rom. 5, 1:
Being justified by faith, we have peace with God. This whole
doctrine is to be referred to that conflict of the terrified
conscience, neither can it be understood apart from that
conflict. Therefore inexperienced and profane men judge ill
concerning this matter, who dream that Christian righteousness
is nothing but civil and philosophical righteousness.

Heretofore consciences were plagued with the doctrine of
works, they did not hear the consolation from the Gospel. Some
persons were driven by conscience into the desert, into
monasteries hoping there to merit grace by a monastic life.
Some also devised other works whereby to merit grace and make
satisfaction for sins. Hence there was very great need to
treat of, and renew, this doctrine of faith in Christ, to the
end that anxious consciences should not be without consolation
but that they might know that grace and forgiveness of sins