_On the contrary,_ Punishment is due to sin. But every sin is
voluntary according to Augustine (De Lib. Arb. iii; Retract. i).
Therefore vengeance should be taken only on those who have deserved
it voluntarily.

_I answer that,_ Punishment may be considered in two ways. First,
under the aspect of punishment, and in this way punishment is not due
save for sin, because by means of punishment the equality of justice
is restored, in so far as he who by sinning has exceeded in following
his own will suffers something that is contrary to this will.
Wherefore, since every sin is voluntary, not excluding original sin,
as stated above (I-II, Q. 81, A. 1), it follows that no one is
punished in this way, except for something done voluntarily.
Secondly, punishment may be considered as a medicine, not only
healing the past sin, but also preserving from future sin, or
conducing to some good, and in this way a person is sometimes
punished without any fault of his own, yet not without cause.

It must, however, be observed that a medicine never removes a greater
good in order to promote a lesser; thus the medicine of the body
never blinds the eye, in order to repair the heel: yet sometimes it
is harmful in lesser things that it may be helpful in things of
greater consequence. And since spiritual goods are of the greatest
consequence, while temporal goods are least important, sometimes a
person is punished in his temporal goods without any fault of his
own. Such are many of the punishments inflicted by God in this
present life for our humiliation or probation. But no one is punished
in spiritual goods without any fault on his part, neither in this nor
in the future life, because in the latter punishment is not
medicinal, but a result of spiritual condemnation.

Reply Obj. 1: A man is never condemned to a spiritual punishment for
another man's sin, because spiritual punishment affects the soul, in
respect of which each man is master of himself. But sometimes a man
is condemned to punishment in temporal matters for the sin of
another, and this for three reasons. First, because one man may be
the temporal goods of another, and so he may be punished in
punishment of the latter: thus children, as to the body, are a
belonging of their father, and slaves are a possession of their
master. Secondly, when one person's sin is transmitted to another,
either by _imitation,_ as children copy the sins of their parents,
and slaves the sins of th