Lactantius — Divine Institutes 6.5
But before I begin to set out the several virtues, virtue itself must be defined, which the philosophers have not defined rightly — what it was or in what things, what work, what office it had. They have therefore kept the name alone, but lost the force and reason and effect. Whatever things they are accustomed to say into a definition of virtue Lucilius gathers and narrates in a few verses, which I prefer to set down lest, while I refute many opinions, I be longer than necessary. 'Virtue, Albinus, is to be able to pay true value for the things in which we are turned about, in which we live: virtue is for a human to know what each thing has; virtue, to know for a human what is right, useful, honorable, what goods, likewise what evils, what useless, base, dishonorable: virtue, to know the end and measure of a thing to be sought; virtue, to be able to pay value to riches…' But when he said good and evil, nothing can be useful or honorable that is not also good, nothing useless and base that is not also evil — which both seems good to the philosophers and Cicero shows in the third book of the work named above.
But knowledge cannot be virtue, because it is not inside us, but comes to us from outside. And what can pass from one to another is not virtue, because virtue is each one's own. Knowledge therefore belongs to another's benefit, because it is set in hearing; virtue is wholly ours, because it is set in the will of doing good. As therefore in making a journey it profits nothing to know the road unless effort and strength for walking are at hand, so indeed knowledge profits nothing if one's own virtue fails. For generally even those who sin, if not perfectly, still sense what is good and evil… Knowledge ought to go ahead of virtue, virtue follow knowledge, because cognition profits nothing unless action also follows. Horace therefore a little better: 'Virtue is to flee vice and first wisdom' — but awkwardly, because he bounded it by a contrary, as if he said: 'good is what is not evil.' For when I do not know what virtue is, I do not know what vice is either. Both therefore need definition.
But let us do what he ought. Virtue is to check anger, to curb desire, to rein lust: for that is to flee vice. For nearly all things that are done unjustly and wickedly rise from these passions. For if the rush of this agitation which is called anger is beaten back, all humans' evil quarrels will be lulled; no one will lie in wait, no one will leap forth… no one will either suffer or do anything shameful. Therefore all crimes and disgraceful acts, when these agitations are calmed by virtue, will be taken from humans' life and manners. Which calming of agitations and passions has this reason, that we do all things rightly. Therefore virtue's whole office is not to sin. Which office indeed one who does not know God cannot fulfill, since ignorance of him from whom goods arise must necessarily drive the imprudent into vices. And so that I may define more briefly and more tellingly the chief offices of each thing: knowledge is to know God, virtue to worship him: in the former wisdom is contained, in the latter justice.
Latin
Sed priusquam singulas uirtutes exponere incipio, determinanda est ipsa uirtus, quam non recte philosophi definierunt, quid esset aut in quibus rebus, quid operis, quid haberet officii. nomen itaque solum retinuerunt, uim uero et rationem et effectum perdiderunt. quaecumque autem in definitionem uirtutis solent dicere, paucis uersibus colligit et enarrat Lucilius, quos malo equidem ponere, ne dum multorum sententias refello, sim longior quam necesse est. uirtus, Albine, est pretium persoluere uerum quis in uersamur, quis uiuimus rebus potesse: uirtus est homini scire id quod quaeque habeat res, uirtus, scire homini rectum utile quid sit, honestum, quae bona, quae mala item, quid inutile turpe inhonestum: uirtus, quaerendae finem rei scire modumque, uirtus, diuitiis pretium persoluere posse, uirtus, id dare quod re ipsa debetur honori: hostem esse atque inimicum hominum morumque malorum, contra defensorem hominum morumque bonorum, hos magni facere, his bene uelle, his uiuere amicum: commoda praeterea patriai prima putare, deinde parentum, tertia iam postremaque nostra . ab his definitionibus, quas poeta breuiter conprehendit, Marcus Tullius traxit officia uiuendi Panaetium Stoicum secutus eaque tribus uoluminibus inclusit. haec autem quam falsa sint mox uidebimus, ut appareat quantum in nos dignatio diuina contulerit, quae nobis aperuit ueritatem. uirtutem esse dixit scire quid sit bonum et malum, quid turpe, quid honestum, quid utile, quid minus. breuius facere potuit, si tantum bonum ac malum diceret, quia nihil potest esse utile uel honestum quod non idem bonum sit, nihil inutile ac turpe quod non idem malum. quod et philosophis uidetur et idem Cicero in tertio supra dicti operis ostendit.
uerum scientia non potest esse uirtus, quia non est intus in nobis, sed ad nos extrinsecus uenit. quod autem transire ab altero ad alterum potest, uirtus non est, quia uirtus sua cuique est. scientia igitur alieni beneficii est, quia posita est in audiendo, uirtus tota nostra est, quia posita est in uoluntate faciendi boni. sicut ergo in itinere celebrando nihil prodest uiam nosse, nisi conatus ac uires suppetant ambulandi, ita uero scientia nihil prodest, si uirtus propria deficiat. nam fere etiam u qui peccant, etsi non perfecte, tamen quid sit bonum et malum sentiunt, et quotiens aliquid improbe faciunt, peccare se sciunt et ideo celare nituntur. sed cum eos boni et mali natura non fallat, cupiditate mala uincuntur, ut peccent, quia deest illis uirtus, id est cupiditas recta et honesta faciendi. ex hoc igitur apparet aliut esse scientiam boni malique, aliut uirtutem, quod potest esse scientia sine uirtute, sicut in plurimis philo-_ sophorum fuit. in quo, quoniam recte ad culpam pertinet non fecisse quae scieris, recte uoluntas praua et uitiosus animus, quem ignoratio excusare non potest, punietur. ergo sicut uirtus non est bonum ac malum scire, ita uirtus est bonum facere, malum non facere. et tamen scientia sic cum uirtute coniuncta est, ut scientia praecedat uirtutem, uirtus sequatur scientiam, quia nihil prodest cognitio, nisi et actio subsequatur. Horatius igitur paulo melius: uirtus est uitium fugere et sapientia prima, sed inepte, quod eam contrario terminauit, ut si diceret: \'bonum est quod malum non est\'. cum enim quid sit uirtus nescio, ne uitium quidem quid sit scio. utrumque igitur indiget definitione, quia natura rei talis est, ut utrumque aut intellegi aut non intellegi sit necesse. uerum nos faciamus quod ille debuit.
uirtus est iram cohibere, cupiditatem conpescere, libidinem refrenare: id est enim uitium fugere. nam fere omnia quae fiunt iniuste atque inprobe, ab his oriuntur adfectibus. si enim commotionis huius quae ira dicitur impetus retundatur, omnes hominum contentiones malae sopientur, nemo insidiabitur, nemo prosiliet ad nocendum. item si cupiditas temperetur, nemo terra marique grassabitur, nemo exercitum ducet, ut rapiat et uastet aliena. item si ardor libidinum conprimatur, omnis aetas et sexus retinebit suam sanctitatem, nemo quidquam pudendum aut patietur aut faciet. ergo uniuersa scelera et flagitia his commotionibus uirtute sedatis ex hominum uita moribusque tollentur. quae sedatio commotionum et adfectuum hanc habet rationem, ut omnia recta faciamus. omne igitur uirtutis officium est non peccare. quo profecto fungi non potest qui deum nescit, quoniam ignoratio eius a quo bona oriuntur, inprudentem inpingat in uitia necesse est. itaque ut breuius et significantius utriusque rei summa officia determinem, scientia est deum nosse, uirtus colere: in illo sapientia, in hoc iustitia continetur.