Ott on Justification

Without special Divine Revelation no one can know with the certainty of faith, if he be in the state of grace (De fide.)

Against the teaching of the Reformers, that the justified possess certainty of faith which excludes all doubts about their justification, the Council of Trent declared: "If one considers his own weakness and his defective disposition, he may well be fearful and anxious as to his state of grace, as nobody knows with the certainty of faith, which permits of no error, that he has achieved the grace of God"

The reason for the uncertainty of the state of grace lies in this that without a special revelation nobody can with certainty of faith know whether or not he has fulfilled all the conditions which are necessary for the achieving of justification. The impossiblity of the certainty of faith, however, by no means excludes a high moral certainty by the testimony of conscience.

The degree of justifying grace is not identical in all the just. (De fide.) Grace can be increased by good works (De Fide.)

As the Reformers wrongly regarded justification as a merely external imputation of Christ's justice, they were obliged also to hold that justification is identical in all men. The Council of Trent, however, declared that the measure of the grace of justification received varies in the individual person who is justified, according to the measure of God's free distribution, and to the disposition and co-operation of the recipient himself.

In regard to the increase of the state of grace, the Council of Trent declared against the Reformers, who asserted that good works are only a fruit of achieved justification, that the justice already in the soul is increased by good work. The various good works are rewarded by different grades of grace.

-Ludwig Ott, Fundamentals of Catholic Dogma, pgs 261-262