4 But has he who has one virtue all virtues? And has he no virtues who lacks one? If this be true, the sentence of the apostle is thereby confirmed. But what I desire is to have the sentence explained, not confirmed, since of itself it stands more sure in our esteem than all the authority of philosophers could make it. And even if what has just been said concerning virtues and vices were true, it would not follow that therefore all sins are equal. For as to the inseparable co-existence of the virtues, this is a doctrine in regard to which, if I remember rightly, what, indeed, I have almost forgotten (though perhaps I am mistaken), all philosophers who affirm that virtues are essential to the right conduct of life are agreed. The doctrine of the equality of sins, however, the Stoics alone dared to maintain in opposition to the unanimous sentiments of mankind: an absurd tenet, which in writing against Jovinianus (a Stoic in this opinion, but an Epicurean in following after and defending pleasure) you have most clearly refuted from the Holy Scriptures. In that most delightful and noble dissertation you have made it abundantly plain that it has not been the doctrine of our authors, or rather of the Truth Himself, who has spoken through them, that all sins are equal. I shall now do my utmost in endeavouring, with the help of God, to show how it can be that, although the doctrine of philosophers concerning virtues is true, we are nevertheless not compelled to admit the Stoics' doctrine that all sins are equal. If I succeed, I will look for your approbation, and in whatever respect I come short, I beg you to supply my deficiencies.
5. Those who maintain that he who has one virtue has all, and that he who lacks one lacks all, reason correctly from the fact that prudence cannot be cowardly, nor unjust, nor intemperate; for if it were any of these it would no longer be prudence. Moreover, if it be prudence only when it is brave, and just, and temperate, assuredly wherever it exists it must have the other virtues along with it. In like manner, also, courage cannot be imprudent, or intemperate, or unjust; temperance must of necessity be prudent, brave, and just; and justice does not exist unless it be prudent, brave, and temperate. Thus, wherever any one of these virtues truly exists, the others likewise exist; and where some are absent, that which may appear in some measure to resemble virtue is not really present.
6. There are, as you know, some vices opposed to virtues by a palpable contrast, as imprudence is the opposite of prudence. But there are some vices opposed to virtues simply because they are vices which, nevertheless, by a deceitful appearance resemble virtues; as, for example, in the relation, not of imprudence, but of craftiness to the said virtue of prudence. I speak here of that craftiness which is wont to be understood and spoken of in connection with the evilly disposed, not in the sense in which the word is usually employed in our Scriptures, where it is often used in a good sense, as, “Be crafty as serpents,” and again, to give craftiness to the simple. It is true that among heathen writers one of the most accomplished of Latin authors, speaking of Catiline, has said: “Nor was there lacking on his part craftiness to guard against danger,” using “craftiness” (astutia) in a good sense; but the use of the word in this sense is among them very rare, among us very common. So also in regard to the virtues classed under temperance. Extravagance is most manifestly opposite to the virtue of frugality; but that which the common people are wont to call niggardliness is indeed a vice, yet one which, not in its nature, but by a very deceitful similarity of appearance, usurps the name of frugality. In the same manner injustice is by a palpable contrast opposed to justice; but the desire of avenging oneself is wont often to be a counterfeit of justice, but it is a vice. There is an obvious contrariety between courage and cowardice; but hardihood, though differing from courage in nature, deceives us by its resemblance to that virtue. Firmness is a part of virtue; fickleness is a vice far removed from and undoubtedly opposed to it; but obstinacy lays claim to the name of firmness, yet is wholly different, because firmness is a virtue, and obstinacy is a vice.
7. To avoid the necessity of again going over the same ground, let us take one case as an example, from which all others may be understood. Catiline, as those who have written concerning him had means of knowing, was capable of enduring cold, thirst, hunger, and patient in fastings, cold, and watchings beyond what any one could believe, and thus he appeared, both to himself and to his followers, a man endowed with great courage. But this courage was not prudent, for he chose the evil instead of the good; was not temperate, for his life was disgraced by the lowest dissipation; was not just, for he conspired against his country; and therefore it was not courage, but hardihood usurping the name of courage to deceive fools; for if it had been courage, it would not have been a vice but a virtue, and if it had been a virtue, it would never have been abandoned by the other virtues, its inseparable companions.
8. On this account, when it is asked also concerning vices, whether where one exists all in like manner exist, or where one does not exist none exist, it would be a difficult matter to show this, because two vices are wont to be opposed to one virtue, one that is evidently opposed, and another that bears an apparent likeness. Hence the hardihood of Catiline is the more easily seen not to have been courage, since it had not along with it other virtues; but it may be difficult to convince men that his hardihood was cowardice, since he was in the habit of enduring and patiently submitting to the severest hardships to a degree almost incredible. But perhaps, on examining the matter more closely, this hardihood itself is seen to be cowardice, because he shrunk from the toil of those liberal studies by which true courage is acquired. Nevertheless, as there are rash men who are not guilty of cowardice, and there are cowardly men who are not guilty of rashness, and since in both there is vice, for the truly brave man neither ventures rashly nor fears without reason, we are forced to admit that vices are more numerous than virtues.
9. Accordingly, it happens sometimes that one vice is supplanted by another, as the love of money by the love of praise. Occasionally, one vice quits the field that more may take its place, as in the case of the drunkard, who, after becoming temperate in the use of drink, may come under the power of niggardliness and ambition. It is possible, therefore, that vices may give place to vices, not to virtues, as their successors, and thus they are more numerous. When one virtue, however, has entered, there will infallibly be (since it brings all the other virtues along with it) a retreat of all vices whatsoever that were in the man; for all vices were not in him, but at one time so many, at another a greater or smaller number might occupy their place.
Source: Letters (New Advent)