20 But our faith thus teaches, that when men fall asleep, they sleep this slumber without knowing good from evil. And the righteous look not forward to their promises, nor do the wicked look forward to their sentence of punishment, until the Judge come and separate those whose place is at His right hand from those whose place is at His left. And be instructed by that which is written, that when the Judge shall sit, and the books be opened before Him and the good and evil deeds recited, then they that have wrought good works shall receive good rewards from Him Who is good; and they that have done evil deeds shall receive evil penalties from the just Judge.
For towards the good, He changes not His nature; and He proves Himself just because He justly condemns many. But towards the evil He changes His nature, in that world where grace is lost in justice; and He proves Himself just to all. And grace will not be joined with justice towards them. Like as grace avails not (to remedy) detriment, so justice (avails not to assist) grace. For grace is far from the judge, but justice urges the judge. If grace be near to any one, let him turn himself towards it, and not deliver himself into the hands of justice, lest it condemn him, exacting for his shortcomings the penalty at his hands. And if grace be far from any one, justice will bring him to the trial, and by it he will be condemned, and go away to the torment.
Source: Demonstrations (New Advent)