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.
Sed iniustitiae genera duo sunt, unum eorum, qui inferunt, alterum eorum, qui ab iis, quibus infertur, si possunt, non propulsant iniuriam. Nam qui iniuste impetum in quempiam facit aut ira aut aliqua perturbatione incitatus, is quasi manus afferre videtur socio; qui autem non defendit nec obsistit, si potest, iniuriae, tam est in vitio, quam si parentes aut amicos aut patriam deserat. 24 Atque illae quidem iniuriae, quae nocendi causa de industria inferuntur, saepe a metu proficiscuntur, cum is, qui nocere alteri cogitat, timet ne, nisi id fecerit, ipse aliquo afficiatur incommodo. Maximam autem partem ad iniuriam faciendam aggrediuntur, ut adipiscantur ea, quae concupiverunt; in quo vitio latissime patet avaritia.
B. Justice.
20 VII. Of the three remaining divisions, the most extensive in its application is the principle by which society and what we may call its "common bonds" are maintained. Of this again there are two divisions—justice, in which is the crowning glory of the virtues and on the basis of which men are called "good men"; and, close akin to justice, charity, which may also be called kindness or generosity.
The first office of justice is to keep one man from doing harm to another, unless provoked by wrong; and the next is to lead men to use common possessions for the common interests, private property for their own.
Public vs. private interests.
21 There is, however, no such thing as private ownership established by nature, but property becomes private either through long occupancy (as in the case of those who long ago settled in unoccupied territory) or through conquest (as in the case of those who took it in war) or by due process of law, bargain, or purchase, or by allotment. On this principle the lands of Arpinum are said to belong to the Arpinates, the Tusculan lands to the Tusculans; and similar is the assignment of private property. Therefore, inasmuch as in each case some of those things which by nature had been common property became the property of individuals, each one should retain possession of that which has fallen to his lot; and if anyone appropriates to himself anything beyond that, he will be violating the laws of human society.