As a rule, the cities take the part of the crown in fights against the feudal nobles, from social reasons, because the landed nobles refuse to recognize the social equality, demanded as of right by their more wealthy citizens; from political reasons, because the central government, thanks to the solidarity between prince and people, is more apt to be influenced by common interests than is the territorial magnate, who serves only his private interests; and finally from economic reasons, because city life can prosper only in peace and safety. The practises of chivalry, such as club law, and private warfare, and the knights’ practise of looting caravans are irreconcilable with the economic means; and therefore, the cities are faithful allies of the guardians of peace and justice, first to the emperor, later on, to the sovereign territorial prince; and when the armed citizenship breaks and pillages some robber baron’s fortress, the tiny drop reflects the identical process happening in the ocean of history. In order successfully to carry this political rôle the city must attract as many citizens as possible, an endeavor also forced on it by purely economic considerations, since both divisions of labor and wealth increase with increased citizenship. Therefore cities favor immigration with all their powers; and once more show in this the polar contrast of their essential difference from the feudal landlords. The new citizens thus attracted into the cities are withdrawn from the feudal estates, which are thereby weakened in power of taxation and military defense in proportion as the cities are strengthened. The city becomes a mighty competitor at the auction, wherein the serf is knocked down to the highest bidder, to the one, that is to say, who offers the most rights. The city offers the peasant _complete liberty_, and in some cases house and courtyard. The principle, “city air frees the peasant” is successfully fought out; and the central government, pleased to strengthen the cities and to weaken the turbulent nobles, usually confirms by charter the newly acquired rights. _The third great move in the progress of universal history is to be seen in the discovery of the honor of free labor_; or better in its rediscovery, it having been lost sight of since those far-off times in which the free huntsman and the subjugated primitive tiller enjoyed the results of their labor. As yet the peasant bears the mark of the pariah and his rights are little respected. But in the wall-girt, well-defended city, the citizen holds his head high. He is a freeman in every sense of the word, free even at law, since we find in the grants of rights to many early enfranchised cities (_Ville-franche_) the provision that a serf residing therein “a year and a day” undisturbed by his master’s claim is to be deemed free.