Thomas Aquinas

“ The bodies of children will be impassible, not through their being unable in themselves to suffer, but through the lack of an external agent to act upon them: because, after the resurrection, no body will act on another, least of all so as to induce corruption by the action of nature, but there will only be action to the effect of punishing them by order of the divine justice. Wherefore those bodies to which pain of sense is not due by divine justice will not suffer punishment. On the other hand, the bodies of the saints will be impassible, because they will lack the capability of suffering ”

“ Accordingly, it must be observed that if one is guided by right reason one does not grieve through being deprived of what is beyond one's power to obtain, but only through lack of that which, in some way, one is capable of obtaining. ”

“ Wherefore the lack of such a grace will not cause sorrow in children who die without Baptism, any more than the lack of many graces accorded to others of the same condition makes a wise man to grieve. ”

“ Freedom from fault does not lessen but increases the pain of punishment: for a man does not grieve less for that he is disinherited or deprived of a limb through no fault of his. Therefore these souls likewise, albeit deprived of so great a good through no fault of theirs, suffer none the less. ”

“ On the contrary, If unbaptized children have interior sorrow after death, they will grieve either for their sin or for their punishment. If for their sin, since they cannot be further cleansed from that sin, their sorrow will lead them to despair. ”

“ We must next consider the various qualities of souls that are stripped of their bodies, according to their respective states; and first we shall treat of the souls which depart this life with original sin only. ”

“ Now punishment denotes sensible pain. Therefore souls which depart this life with original sin alone, suffer from a bodily fire and are tormented with the pain of fire.
Objection 2: Further, a greater fault deserves a greater punishment. Now original sin is greater than venial, because it contains more aversion, since it deprives its subject of grace, whereas venial sin is compatible with grace; and again because original sin is punished eternally, whereas venial sin is punished temporally. Seeing then that venial sin is deserving of the punishment of fire, much more so is original sin. ”

“ But children were never adapted to possess eternal life, since neither was this due to them by virtue of their natural principles, for it surpasses the entire faculty of nature, nor could they perform acts of their own whereby to obtain so great a good. ”

“ Although unbaptized children are separated from God as regards the union of glory, they are not utterly separated from Him: in fact they are united to Him by their share of natural goods, and so will also be able to rejoice in Him by their natural knowledge and love. ”

“ If, on the other hand, they be passible, since everything passible suffers of necessity in the presence of the active, it follows that in the presence of active sensible bodies they will suffer sensible punishment. ”