" The misuse of language contributes also to the belief that labor unions are a product of modern industrial development. They are nothing of the kind. On the contrary, they are a throwback to a preindustrial period, to the guilds that were the characteristic form of organization of both merchants and craftsmen in the cities and city-states that grew out of the feudal period. Indeed, the modern labor union can be traced back even further, nearly 2,500 years to an agreement reached among medical men in Greece. "

― Milton Friedman , Free to Choose: A Personal Statement