Thomas Aquinas

“ Action and passion belong to the moral order, in so far as they are voluntary. And therefore in so far as they are voluntary in respect of wills that differ, they are two distinct things, and good can be in one of them while evil is in the other. ”

“ On the contrary, Every agent intends to attain good and avoid evil. If therefore by the external action no further goodness or malice be added, it is to no purpose that he who has a good or an evil will, does a good deed or refrains from an evil deed. ”

“ On the other hand it happens sometimes that that which is subordinate to something else, has some aspect of goodness in itself, besides the fact of its being subordinate to some other good: thus a palatable medicine can be considered in the light of a pleasurable good, besides being conducive to health. ”

“ But if this prove impossible, as long as the will is perfect, so as to realize the operation if it could; the lack of perfection derived from the external action, is simply involuntary. Now just as the involuntary deserves neither punishment nor reward in the accomplishment of good or evil deeds, so neither does it lessen reward or punishment, if a man through simple involuntariness fail to do good or evil. ”

“ As stated in Ethic. vi, 12, a moral virtue is ordained to the act of that virtue, which act is the end, as it were, of that virtue; whereas prudence, which is in the reason, is ordained to things directed to the end. ”