3. Natural equity seems to require every one to be deprived of the good against which he takes action, as thereby he renders himself unworthy of that good. Hence by process of civil justice whoever offends against the commonwealth is deprived of the society of the commonwealth altogether, either by death or by perpetual banishment. Nor is the time taken by his offence considered, but the power against which he has offended. He then who sins against his last end and against charity, which is the foundation of the society of the Blessed and of wayfarers on the road to Blessedness, ought to be punished eternally, though his sin took only a short space of time.
4. In the divine judgement the will is taken for the deed: because as men see what is done outwardly, so does God view the hearts of men. But whoever for the sake of some temporal good has turned himself away from the final end, which is possessed for ever, has preferred the temporal enjoyment of that good to the eternal enjoyment of the last end: much more then, it clearly appears, would he have willed the enjoyment of that temporal good for all eternity. Therefore according to the divine judgement he ought to be punished as though he had gone on sinning for eternity. And beyond question, for eternal sin eternal punishment is due.
Hence it is said: These shall go into everlasting punishment, but the just into life everlasting (Matt. xxv, 46).
Hereby is excluded the error of them who say that the punishment of the wicked will at some time come to an end. This position seems to have had its foundation in the position of certain philosophers* who said that all punishments were purgatorial, and consequently at some time terminable. And this position seems plausible, as well by the custom of mankind, for human laws inflict penalties as means and in a manner medicines for the amendment of vices; as also by reason, for if punishment were inflicted, not for the sake of something else, but for its own sake, it would follow that the authority punishing took delight in punishments for their own sake, which is inconsistent with the goodness of God: it needs must be then that punishment is inflicted for the sake of something else, and no more suitable end appears than the amendment of vices. There seems therefore reason for saying that all punishments are purgatorial, and consequently terminable, since whatever is matter of purgation is accidental in regard of the creature, and can be removed without consumption of its substance.
In reply it must be allowed that punishments are inflicted by God, not for their own sake, as though God took delight in them, but for the sake of something else, namely, in view of the order which He wishes to impose on creatures, in which order the good of the universe consists (B. II, Chap. XLV). The order of the universe requires all things to be dispensed by God in due proportion, in weight, number, and measure (Wisd. xi, 21). But as rewards answer proportionably to virtuous actions, so punishments to sins; and to some sins everlasting punishments are proportionable. God then inflicts eternal punishments on some sins, that the due order may be observed in things, which order proves His wisdom.
But even though one were to allow that all punishments are applied to the amendment of vices, and to no other purpose, not on that account are we obliged to suppose that all punishments are purgatorial and terminable. For even by human laws some men are punished by death, not for their amendment, but for the amendment of others: hence it is said: For the scourging of the pestilent man, the fool shall be wiser (Prov. xix, 25).* Sometimes also human laws drive men out of the State into perpetual banishment, that the State may be purer by being rid of them: hence it is said: Cast out the scorner, and the quarrel will go out with him, and suits and brow- beatings will cease (Prov. xxii, 10). Even then though punishments be employed only for the reformation of manners, it may very well be that by the judgement of God some men ought to be for ever separated from the society of the good and eternally punished, that by the fear of everlasting punishment men may cease to sin, and the society of the good may be the purer for their separation, as it is said: There shall not enter therein anything unclean, or making abomination or lying (Apoc. xxi, 27).*
3.144 : Of the Punishment due to Mortal and Venial Sins respectively in regard to the Last End
3.146 : That Sins are punished also by the experience of something Painful