Hygiene, little studied in those days, gave birth to several precautionary measures. Indeed, it was necessary to study it when epidemics were abroad, and epidemics were both frequent and deadly. The private slaughter-houses, and still more those of the Butchers' Guild, were periodically inspected and moved out of the towns into the suburbs. The numerous rules and dues which were imposed on this rich guild, which, with its slaughterers and knackers, formed a formidable and powerful company, appear to have been balanced by considerable privileges. At Paris, for instance, the Grande Boucherie, as it was called, possessed a monopoly extending to the suburbs, by which the masters, reduced to a small number who succeeded one another from father to son, had the sole right of selling or buying live animals or meat, as well as sea and fresh-water fish. The constant relations between the craft guilds and the authorities gave them a place of their own; but, besides this, they led to the creation of guilds of an entirely official character. The guilds of the measurers (_mesureurs_ and _jaugeurs_), who verified the capacity of earthenware jars, barrels, bushels, etc., or of the criers (_crieurs_), who cried in the streets the contents of their jugs--wine for instance--and offered them to the passers-by to taste,[79] were in fact combinations of government officials. These trades were peculiar in this respect, that those who plied them were in receipt of a salary out of their official takings, and that they might not exceed a certain number; and also that they held a monopoly, since every one was obliged to employ them. Through them we can pass to the second aspect of the communal or lordly legislation which regulated the provision trades, viz. the fiscal aspect. It was no longer in the interests of the consumer that the Commune kept, for instance, the monopoly of salt, buying as cheaply and selling as dearly as possible. It was for its own benefit that it instituted customs, dues, and tolls, levied on food-stuffs, which therefore fell more heavily on the poor than on the rich; their variation was simple--when the poorer classes had their way the dues went down, when the rich were in power they went up. Things are just the same nowadays, in spite of the fine phrases with which the fluctuations of commercial policy in great states are disguised. But since, in speaking of guilds, we have been led to speak of social classes, we must now describe their classification in those centres where the system was most fully developed,--that is where guilds, instead of being subjects, were ruling powers.