Thomas Aquinas

“ Good is either the end, or something referred to the end. And therefore, since the good of the worker consists in the work, this fact also, that virtue makes the worker good, is referred to the work, and consequently, to the power. ”

“ But if man's will is confronted with a good that exceeds its capacity, whether as regards the whole human species, such as Divine good, which transcends the limits of human nature, or as regards the individual, such as the good of one's neighbor, then does the will need virtue. And therefore such virtues as those which direct man's affections to God or to his neighbor are subjected in the will, as charity, justice, and such like. ”

“ One accident is said to be the subject of another, not as though one accident could uphold another; but because one accident inheres to substance by means of another, as color to the body by means of the surface ”

“ But the practical intellect is the subject of prudence. For since prudence is the right reason of things to be done, it is a condition thereof that man be rightly disposed in regard to the principles of this reason of things to be done, that is in regard to their ends, to which man is rightly disposed by the rectitude of the will, just as to the principles of speculative truth he is rightly disposed by the natural light of the active intellect. ”

“ Some virtues are directed to the good of moderated passion, which is the proper good of this or that man: and in these cases there is no need for virtue in the will, for the nature of the power suffices for the purpose, as we have said. ”

“ Secondly, a habit may confer not only aptness to act, but also the right use of that aptness: for instance, justice not only gives man the prompt will to do just actions, but also makes him act justly. ”

“ Sometimes it is taken for the very existence of the living thing: in this way it belongs to the essence of the soul, which is the principle of existence in the living thing. But sometimes "to live" is taken for the operation of the living thing: in this sense, by virtue we live righteously, inasmuch as by virtue we perform righteous actions. ”

“ And since virtue is that "which makes its possessor good, and his work good likewise," these latter habits are called virtuous simply: because they make the work to be actually good, and the subject good simply. But the first kind of habits are not called virtues simply: because they do not make the work good except in regard to a certain aptness, nor do they make their possessor good simply. For through being gifted in science or art, a man is said to be good, not simply, but relatively ”

“ In this way it is impossible for one virtue to be in two powers: since diversity of powers follows the generic conditions of the objects, while diversity of habits follows the specific conditions thereof: and so wherever there is diversity of powers, there is diversity of habits ”

“ And since good, and, in like manner, being, is said of a thing simply, in respect, not of what it is potentially, but of what it is actually: therefore from having habits of the latter sort, man is said simply to do good, and to be good ”