The stories of fortunes made by merchants who travelled among simple native tribes with cargoes of glass beads and were able to exchange these gaudy baubles for gold or rubber or other commodities which are valuable in civilized countries, have often been told, and opportunities for trading of this kind must have been very much more frequent when communication was comparatively difficult.  Value to a great extent being determined by local convention and local habit, the profits of the trader were likely to be considerably increased the further he got from his home market.  If he took away with him plenty of things which were in abundant supply at home and consequently cheap, he would almost certainly be able to bring back a large number of things which were plentiful in a far-away community, and consequently cheap for him to acquire, and scarce in his own district and consequently sure of a good market.  This difference of standard of value in different countries was a great stimulus to foreign trade, also a great help to bringing mankind together, though it sometimes ended in disillusionment.  It has been asserted that even within the memory of man an English merchant traded with a primitive community in which gold and silver were exchangeable weight for weight.  For some years he did a very pleasant and profitable trade by taking a cargo of silver and bringing back with him the same weight in gold, the value of which in England happened to be sixteen times as great, or more.  Unfortunately, when he made his last voyage he was met at the mouth of the river by a friendly native, who informed him that the community was waiting for him with tomahawks, and he hastily put to sea again.  For the rest of his life he cherished a grievance against this curious people with which he had dealt, according to his own view, on perfectly equitable terms, having sold them a commodity at a price to which they were accustomed, and which they regarded as quite correct, with the result that they proposed to murder him because they found that the price was not in accordance with that current in other parts of the world.

By this business of exchange of commodities between one community and another, the process of specialization or division of labour which has already been referred to as its basis has been developed to extraordinary lengths.  Its effect has been to increase enormously the wealth available, while at the same time the concentration of the individual has narrowed down his work so that he now no longer specializes on making one commodity, but on making a part of a fraction of a commodity.