Article I: On the Mean of Virtue

St. Thomas, I-II, q. 64, a. 1, 2, 3; De Virt. q. 1, a. 13.

600. The saying: "Moral virtue is in the mean":

1. Is not to be understood of a mean according to essence and by reason of habit, as if it signified that virtue is essentially between two extreme vices, one of which is opposed to it by excess, the other by defect: for this is false concerning the virtue of justice, to which injustice alone is opposed. Besides, by the same sin one sins simultaneously by excess and by defect, for he who gives less than he ought to one gives more than he can to another or to himself; and if someone gives more than he ought to another, he is already not just but liberal.

2. But it is to be understood causally, of the mean according to effect and by reason of the object, and it signifies that virtue has for its object a mean between excess (more) and defect (less) in its proper matter: for it brings it about that our appetite chooses operations or passions neither more nor less, but precisely in that measure which right reason dictates. Thus for temperance, excess in the matter consists in using delights more than one ought, defect in not using them when one ought, and the mean which is the object of temperance is to use delights as, when, in what way... one ought.

It is proved: The good of moral virtue is in adequation or conformity to the rule, that is, to right reason, without discord from it. But adequation is a mean between excess, by which something surpasses the measure, and defect, by which it falls short of it or does not attain it. Therefore the good of moral virtue is in a mean.

But if virtue is called the ultimate of a power, which indicates the highest, not a mean; - this is to be understood according to the perfection of the act, for thus virtue is at the summit of perfection; but not according to the quantity of the matter, because thus virtue is in a mean.

3. But the sense is not of a mean by reason of the subject and according to the mere measure of our weak condition, namely, that virtue is to be exercised moderately in such a way that man cannot tend to something greatest; - for the greatest is sometimes conformable to reason, as is clear concerning fortitude, magnanimity, virginity, etc.; and yet in this case virtue is still in a mean, because excess is to tend toward that greatest thing when one ought not.

601. The mean of virtue is the mean of reason, because it is conformity to the measure of right reason, which measure it does not exceed and from which it does not depart: but between excess and defect, adequation to the measure holds the mean. Hence it is defined: the property of virtue by which it is so concerned with its matter that it guards against excess and defect. Reason establishes that mean, dictates it, and imposes it on the moral virtues through prudence; whence St. Thomas says that "that mean belongs to prudence as regulating and measuring, to moral virtue as measured and regulated" (a. 3); therefore prudence is in the mean because it itself is the measure of moral virtue.

602. The mean of reason is sometimes the mean of the thing, namely in justice, insofar as reason dictates to justice to pay what is owed according to equality, or to give a thing equal to the person of another or to the thing (whether arithmetically or proportionally), neither more nor less.

For reason determines the mean of a virtue in its proper matter. But justice is concerned with operations which consist in exterior things without respect to the diverse conditions of the one operating. Therefore the mean of justice consists in a thing determined according to itself, without respect to the one operating, insofar namely as it gives to each what he is owed, neither more nor less. And thus the mean of reason is the mean of the thing.

But in the other moral virtues, which are concerned with interior passions, the mean of reason is taken by comparison to us, whence it varies according to persons, qualities, circumstances, and diverse relations to passions. Thus excess in drink for one man is not excess for another.

603. Observations. - 1. The intellectual virtues also are in the mean of the thing. The good of the intellect is truth, which depends on things, which are the measure of our intellect. "Therefore in this way the good of intellectual virtue consists in a certain mean through conformity to the thing itself, according as it says that what is, is, or that what is not, is not; in which the account of the true consists. Excess is according to a false affirmation by which it is said that what is not, is; but defect is taken according to a false negation by which it is said that what is, is not" (a. 3).

2. Furthermore, practical intellectual virtues have the account of a rule as to our works, and thus they are in the mean of reason like the rule itself which imposes the mean. Thus prudence imposes the mean on moral acts and virtues, and art on artifacts.

3. Certain theologians say that the virtues of Religion and Penance are not in the mean; but this is false: for although under one respect there cannot be excess in their matter, insofar as worship rendered to God and satisfaction for sins cannot be excessive in quantity, nevertheless under other respects - quality, mode, time, etc. - there is excess in their matter.