The comparatively simple organization of feudal society broke down under the stress of these changes; a middle class, consisting of neither lords nor villeins, was needed to cope with industry and commerce. Handworkers also were required, so that from the middle of the fourteenth century we find a regular flight from the land to the towns in progress. Another great change took place. No one had been rich according to modern notions in the early Middle Ages, and no one had been destitute; there was no need of a Poor Law. But with the expansion of the sphere of men's operations, the differences between the poor and the rich began to increase. There is little to choose between a slow runner and a swift when the race covers only ten yards; there is more when it covers a hundred, and a great deal when it covers a mile. So, too, when operations are limited to the village market, ability has a limited scope, and the able financier does not grow so very much richer than his neighbour. But when his market comprises a nation, his means for acquiring wealth are extended; the rich become richer, and the poor, comparatively at any rate, poorer. Hence, when in the fourteenth and following centuries the national market expands into a world market, we find growing up side by side capitalism and destitution; and the reason why there are so many millionaires and so much destitution to-day, compared with earlier times, is that the world is now one market, and the range of operations is only limited by the globe. The control of the world's supplies tends to get into the hands of a few big producers or operators instead of being in the hands of a vast number of small ones; and this has come about through ever-expanding markets and ever-increasing specialization. Even whole nations specialize more or less; some produce the corn-supply of the world, some its coal, some its oil, and some do its carrying trade. It is now a question whether there should not be some limits to this process, and it is asked whether a nation or empire should not be self-supporting, irrespective of the economic advantages of expansion and specialization, and of the fact that the more self-supporting it is, the less trade can it do with others; for it cannot export unless it imports, and if each nation makes everything it wants itself it will neither sell to, nor buy from, other nations.