On the other hand, sin can be the punishment of sin accidentally in three ways.  First, when one sin is the cause of another, by removing an impediment thereto.  For passions, temptations of the devil, and the like are causes of sin, but are impeded by the help of Divine grace which is withdrawn on account of sin.  Wherefore since the withdrawal of grace is a punishment, and is from God, as stated above (Q. 79, A. 3), the result is that the sin which ensues from this is also a punishment accidentally.  It is in this sense that the Apostle speaks (Rom. 1:24) when he says:  “Wherefore God gave them up to the desires of their heart,” i.e. to their passions; because, to wit, when men are deprived of the help of Divine grace, they are overcome by their passions.  In this way sin is always said to be the punishment of a preceding sin.  Secondly, by reason of the substance of the act, which is such as to cause pain, whether it be an interior act, as is clearly the case with anger or envy, or an exterior act, as is the case with one who endures considerable trouble and loss in order to achieve a sinful act, according to Wis. 5:7:  “We wearied ourselves in the way of iniquity.”  Thirdly, on the part of the effect, so that one sin is said to be a punishment by reason of its effect.  In the last two ways, a sin is a punishment not only in respect of a preceding sin, but also with regard to itself.

Reply Obj. 1:  Even when God punishes men by permitting them to fall into sin, this is directed to the good of virtue.  Sometimes indeed it is for the good of those who are punished, when, to wit, men arise from sin, more humble and more cautious.  But it is always for the amendment of others, who seeing some men fall from sin to sin, are the more fearful of sinning.  With regard to the other two ways, it is evident that the punishment is intended for the sinner’s amendment, since the very fact that man endures toil and loss in sinning, is of a nature to withdraw man from sin.

Reply Obj. 2:  This objection considers sin essentially as such:  and the same answer applies to the Third Objection. ________________________

THIRD ARTICLE [I-II, Q. 87, Art. 3]

Whether Any Sin Incurs a Debt of Eternal Punishment?

Objection 1:  It would seem that no sin incurs a debt of eternal punishment.  For a just punishment is equal to the fault, since justice is equality:  wherefore it is written (Isa. 27:8):  “In measure against measure, when it shall be cast off, thou shalt judge it.”  Now sin is temporal.  Therefore it does not incur a debt of eternal punishment.

Obj. 2:  Further, “punishments are a kind of medicine” (Ethic. ii, 3).  But no medicine should be infinite, because it is directed to an end, and “what is directed to an end, is not infinite,” as the Philosopher states (Polit. i, 6).  Therefore no punishment should be infinite.

Obj. 3:  Further, no one does a thing always unless he delights in it for its own sake.  But “God hath not pleasure in the destruction of men” [Vulg.:  ’of the living’].  Therefore He will not inflict eternal punishment on man.