As states grow greater and men’s manners gentler, the ranks of slavery are less and less liable to be recruited through the agency of war.(410) It then becomes necessary to have recourse to the family to keep up their number, which makes their condition much more endurable, and which supposes that it has been made more endurable in other respects beforehand. Modern states, are, as a rule, larger than the ancient were. The Germans had, long before the time of Charlemagne, treated prisoners of war of German origin more mildly than those of Gallic or Slavic origin.(411) The condition of the latter even improved from the time that nations began to think of making permanent conquests. Since the Slavic wars of the tenth century, certainly since the Lithuanian contests, it seems that prisoners of war were not reduced to slavery.(412) Chivalry, and allowing prisoners to go free, on their word of honor, contributed largely to this result. The more productive agriculture is, the more numerous the wants of land owners, the more extensive the division of labor and commercial intercourse become, the easier it is for a large class of the community to obtain support for themselves and families without cultivating land of their own. (Wages.) When exchanges through the medium of money become customary, the chief argument for slavery disappears; and the strong, rich and able man can, without having recourse to force, command the labor of other men. Every further advance in economic culture must necessarily help forward in this direction. Thus, without the plow, for instance, we should all be really only so many _glebæ adscripti_. It is due especially to the ever increasing perfection of tools, machines and operations, that the slave of antiquity was transformed into the serf of the middle ages, and afterwards into the day laborer of modern times.(413) It is more particularly to be remarked, that machines, since 1750, “first made the constitutional liberty of many, instead of the feudal freedom of a few, possible.” (_Schäffle._) Section LXXI. Disadvantages Of Slavery.