M. Tulli Ciceronis De Officiis Liber Secundus

[17] Cum igitur hic locus nihil habeat dubitationis, quin homines plurimum hominibus et prosint et obsint, proprium hoc statuo esse virtutis, conciliare animos hominum et ad usus suos adiungere. Itaque, quae in rebus inanimis quaeque in usu et tractatione beluarum fiunt utiliter ad hominum vitam, artibus ea tribuuntur operosis, hominum autem studia, ad amplificationem nostrarum rerum prompta ac parata, virorum praestantium sapientia et virtute excitantur. [18] Etenim virtus omnis tribus in rebus fere vertitur, quarum una est in perspiciendo, quid in quaque re verum sincerumque sit, quid consentaneum cuique, quid consequens, ex quo quaeque gignantur, quae cuiusque rei causa sit, alterum cohibere motus animi turbatos, quos Graeci pathe nominant, appetitionesque, quas illi hormas, oboedientes efficere rationi, tertium iis, quibuscum congregemur, uti moderate et scienter, quorum studiis ea, quae natura desiderat, expleta cumulataque habeamus, per eosdemque, si quid importetur nobis incommodi, propulsemus ulciscamurque eos, qui nocere nobis conati sint, tantaque poena adficiamus, quantam aequitas humanitasque patiatur. VIRTUE 17 Since, therefore, there can be no doubt on this point, that man is the source of both the greatest help and the greatest harm to man, I set it down as the peculiar function of virtue to win the hearts of men and to attach them to one's own service. And so those benefits that human life derives from inanimate objects and from the employment and use of animals are ascribed to the industrial arts; the cooperation of men, on the other hand, prompt and ready for the advancement of our interests, is secured through wisdom and virtue [in men of superior ability]. 18 And, indeed, virtue in general may be said to consist almost wholly in three properties; the first is Wisdom, the ability to perceive what in any given instance is true and real, what its relations are, its consequences, and its causes; the second is Temperance, the ability to restrain the passions and make the impulse's obedient to reason; and the third is Justice, the skill to treat with consideration and wisdom those with whom we are associated, in order that we may through their cooperation have our natural wants supplied in full and overflowing measure, that we may ward of any impending trouble, avenge ourselves upon those who have attempted to injure us, and visit them with such retribution as justice and humanity will permit. Source: Marcus Tullius Cicero. De Officiis. Translated by Walter Miller. Loeb Edition. Cambridge: Harvard University Press, 1913. http://www.stoics.com