After this must be considered specific habitudes. And because habitudes, as was said, are distinguished through good and bad, first one must speak of good habitudes, which are virtues and other things adjoined to them, namely, gifts, beatitudes, and fruits; second, of bad habitudes, namely vices and sins. Now, about virtues, five things must be considered: first, the essence of virtue, second, its subject; third, the division of virtue; fourth, the cause of virtue; five, certain properties of virtue. About the first, four things must be asked. First, whether human virtue is habitude. Second, whether it is working habitude [habitus operativa]. Third, whether it is good habitude. Fourth, the definition of virtue.
To the first one proceeds thus. It seems that human virtue is not habitude. For virtue is the limit of power [ultimus potentiae], as is said in De Caelo I. But the limit of each thing is traced back to the genus of which it is the limit, as the point to the genus of the line. Therefore virtue is traced back to the genus of power, and not to the genus of habitude.
Further, Augustine says, in De Libero Arbit. II, that virtue is good use of free choice. But use of free choice is act. Therefore virtue is not habitude but act.
Further, we do not merit by habitudes but by acts; otherwise a human being would continuously merit, even sleeping. But we merit by virtues. Therefore virtues are not habitudes but acts.
Further, Augustine says, in the book De moribus Eccles., that virtue is order of love. And in the book of eighty-three quest. he says that ordering that is called virtue is enjoying what is to be enjoyed and using what is to be used. But order, or ordering, names either act or relatedness. Therefore virtue is not habitude, but act or relatedness.
Further, just as there are human virtues, there are natural virtues. But natural virtues are not habitudes, but sorts of powers. Therefore neither are human virtues.
But contrariwise is that the Philosopher, in the book Predicament., posits kind of knowledge and virtue to be habitude.
I reply that it must be said that virtue names a kind of completion of power. But the completion of anything is considered chiefly in ordering to its end. But the end of power is act. Wherefore power is said to be complete according as it is determined to its act. But there are sorts of powers that are according to themselves determined to their acts, like active natural powers, and therefore such natural powers according to themselves are called virtues. But rational powers, which are proper to human beings, are not determined to one but have themselves indeterminate to many, are determined to act through habitude, as is obvious from what was said above. And therefore human virtues are habitudes.
Therefore to the first it must be said that sometimes virtue is said of that to which virtue is, to wit, either the object of virtue or its act, just as faith is sometimes called that which is believed, sometimes the believing itself, and sometimes the habitude itself by which one believes. Thus when it is said that virtue is the limit of power, 'virtue' is taken for the object of virtue. For that limit in which the power is able to be is that which is named the virtue of the thing, just as, if someone can carry a hundred pounds and no more, his power is considered according to a hundred pounds and not sixty. But the objection proceeded as if virtue were the limit of power essentially.
To the second it must be said that good use of free choice is said to be virtue according to the same reason, to wit, because it is that to which virtue is directed as its proper act. For the act of virtue is nothing other than good use of free choice.
To the third it must be said that we are said to merit something in two ways: (1) in one way, as by merit itself, in the way we are said to run by running, and in this way we merit by acts; (2) in another way, we are said to merit something as the principle of merit, and in this way we are said to run by moving power, and thus we are said to merit by virtues and habitudes.
To the fourth it must be said that virtue is called order or ordering of love as that to which it is virtue, for love in us is ordered through virtue.
To the fifth it must be said that natural powers are determined of themselves to one, but not rational powers. And therefore it is not similar, as was said.
[Thomas Aquinas, ST 2-1.55.prol & 2-1.55.1, my translation. The Latin is here, the Dominican Fathers translation is here.]
Virtue, of course, while not by any means the only kind of habitude, is the summit of them all, so it is essential for any serious study of habitude, and foundational for any study of human society and civilization. A key concept that is clearly in play here is that habitude is a principle of ordering and determination for actions that can in some way be otherwise (and thus for what is in some way fitting or appropriate rather than necessary), and in the case of virtue, for free actions.
