22. Cultivation by slaves cannot exist in great societies.

Thus when men are formed into great societies, the recruits of slaves are not sufficiently numerous to support the consumption which the cultivation requires. And although they supply the labour of men by that of beasts, a time will come, when the lands can no longer be worked by slaves. The practice is then continued only for the interior work of the house, and in the end it is totally abolished; because in proportion as nations become polished, they form conventions for the exchange of prisoners of war. These conventions are the more readily made, as every individual is very much interested to be free from the danger of falling into a state of slavery.