in the same relation to matters of action, as the indemonstrable principle does to matters of speculation (Ethic. vii, 8).  Therefore when the soul is so disordered by sin as to turn away from its last end, viz.  God, to Whom it is united by charity, there is mortal sin; but when it is disordered without turning away from God, there is venial sin.  For even as in the body, the disorder of death which results from the destruction of the principle of life, is irreparable according to nature, while the disorder of sickness can be repaired by reason of the vital principle being preserved, so it is in matters concerning the soul.  Because, in speculative matters, it is impossible to convince one who errs in the principles, whereas one who errs, but retains the principles, can be brought back to the truth by means of the principles.  Likewise in practical matters, he who, by sinning, turns away from his last end, if we consider the nature of his sin, falls irreparably, and therefore is said to sin mortally and to deserve eternal punishment:  whereas when a man sins without turning away from God, by the very nature of his sin, his disorder can be repaired, because the principle of the order is not destroyed; wherefore he is said to sin venially, because, to wit, he does not sin so as to deserve to be punished eternally.

Reply Obj. 1:  Mortal and venial sins are infinitely apart as regards what they turn away from, not as regards what they turn to, viz. the object which specifies them.  Hence nothing hinders the same species from including mortal and venial sins; for instance, in the species “adultery” the first movement is a venial sin; while an idle word, which is, generally speaking, venial, may even be a mortal sin.

Reply Obj. 2:  From the fact that one sin is mortal by reason of its species, and another venial by reason of its species, it follows that this difference is consequent to the specific difference of sins, not that it is the cause thereof.  And this difference may be found even in things of the same species, as stated above.

Reply Obj. 3:  The reward is intended by him that merits or acts virtu[ous]ly; whereas the punishment is not intended by the sinner, but, on the contrary, is against his will.  Hence the comparison fails. ________________________

SIXTH ARTICLE [I-II, Q. 72, Art. 6]

Whether Sins of Commission and Omission Differ Specifically?

Objection 1:  It would seem that sins of commission and omission differ specifically.  For “offense” and “sin” are condivided with one another (Eph. 2:1), where it is written:  “When you were dead in your offenses and sins,” which words a gloss explains, saying:  “‘Offenses,’ by omitting to do what was commanded, and ‘sins,’ by doing what was forbidden.”  Whence it is evident that “offenses” here denotes sins of omission; while “sin” denotes sins of commission.  Therefore they differ specifically, since they are contrasted with one another as different species.