If these errors are successfully avoided, all the labour and pains expended upon problems that are morally right and worth the solving will be fully rewarded. Such a worker in the field of astronomy, for example, was Gaius Sulpicius, of whom we have heard; in mathematics, Sextus Pompey, whom I have known personally; in dialectics, many; in civil law, still more. All these professions are occupied with the search after truth; but to be drawn by study away from active life is contrary to moral duty. For the whole glory of virtue is in activity; activity, however, may often be interrupted, and many opportunities for returning to study are opened. Besides, the working of the mind, which is never at rest, can keep us busy in the pursuit of knowledge even without conscious effort on our part. Moreover, all our thought and mental activity will be devoted either to planning for things that are morally right and that conduce to a good and happy life, or to the pursuits of science and learning. With this we close the discussion of the first source of duty. *20* VII. De tribus autem reliquis latissime patet ea ratio, qua societas hominum inter ipsos et vitae quasi communitas continetur; cuius partes duae,[20] iustitia, in qua virtutis est splendor maximus, ex qua viri boni nominantur, et huic coniuncta beneficentia, quam eandem vel benignitatem vel liberalitatem appellari licet. Sed iustitiae primum munus est, ut ne cui quis noceat nisi lacessitus iniuria, deinde ut communibus pro communibus utatur, privatis ut suis. *21* Sunt autem privata nulla natura, sed aut vetere occupatione, ut qui quondam in vacua venerunt, aut victoria, ut qui bello potiti sunt, aut lege, pactione, condicione, sorte; ex quo fit, ut ager Arpinas Arpinatium dicatur, Tusculanus Tusculanorum; similisque est privatarum possessionum discriptio.[21] Ex quo, quia suum cuiusque fit eorum, quae natura fuerant communia, quod cuique obtigit, id quisque teneat; e quo[22] si quis sibi appetet, violabit ius humanae societatis. #Ep. IX, ad Archytam, 358 A# *22* Sed quoniam, ut praeclare scriptum est a Platone, non nobis solum nati sumus ortusque nostri partem patria vindicat, partem amici, atque, ut placet Stoicis, quae in terris gignantur, ad usum hominum omnia creari, homines autem hominum causa esse generatos, ut ipsi inter se aliis alii prodesse possent, in hoc naturam debemus ducem sequi, communes utilitates in medium afferre mutatione officiorum, dando accipiendo, tum artibus, tum opera, tum facultatibus devincire hominum inter homines societatem. *23* Fundamentum autem est iustitiae fides, id est dictorum conventorumque constantia et veritas. Ex quo, quamquam hoc videbitur fortasse cuipiam durius, tamen audeamus imitari Stoicos, qui studiose exquirunt, unde verba sint ducta, credamusque, quia fiat, quod dictum est, appellatam fidem.