Did all his views terminate in the consequences of each act of his own, his benevolence and humanity, as well as his self-love, might often prescribe to him measures of conduct very different from those which are agreeable to the strict rules of right and justice.
Thus, two men pull the oars of a boat by common convention for common interest, without any promise or contract; thus gold and silver are made the measures of exchange; thus speech and words and language are fixed by human convention and agreement.

Whatever is advantageous to two or more persons, if all perform their part; but what loses all advantage if only one perform, can arise from no other principle There would otherwise be no motive for any one of them to enter into that scheme of conduct.
[Footnote: This theory concerning the origin of property, and consequently of justice, is, in the main, the same with that hinted at and adopted by Grotius, 'Hinc discimus, quae fuerit causa, ob quam a primaeva communione rerum primo mobilium, deinde et immobilinm discessum est: nimirum quod cum non contenti homines vesci sponte natis, antra habitare, corpore aut nudo agere, aut corticibus arborum ferarumve pellibus vestito, vitae genus exquisitius delegissent, industria opus fuit, quam singuli rebus singulls adhiberent.

Quo minus autem fructus in commune conferrentur, primum obstitit locorum, in quae homines discesserunt, distantia, deinde justitiae et amoris defectus, per quem fiebat, ut nee in labore, nee in consumtione fructuum, quae debebat, aequalitas servaretur.

Simul discimus, quomodo res in proprietatem iverint; non animi actu solo, neque enim scire alii poterant, quid alil suum esse vellent, ut eo abstinerent, et idem velle plures poterant; sed pacto quodam aut expresso, ut per divisionem, aut tacito, ut per occupationem.' De jure belli et pacis.Lib.ii.cap.2.

sec.2.art.