Division of labor and exchange of goods have existed in some form almost from the beginning of organized society. In a very early stage people found by experience the advantage of each worker devoting himself to the production of certain things in which he was most skilled. The primitive fisherman whose preference or skill led him to follow fishing would frequently have a surplus of fish. Another man might be particularly adept in making spears, but as he did not need for his own use all that he could make he was glad to exchange his surplus for other things he needed, such as fish or skins. This system of exchange, known as barter, was crude and clumsy. The man with a surplus of fish had to find someone with a surplus of spears or furs which he was willing to exchange for fish. Even then the terms of the trade were difficult to arrange. A spear was worth more than a fish, but it could not be divided; so to effect a trade the owner of the spear would be compelled to take more fish than he needed. Under a system of barter the difficulty increases with the number of articles to be exchanged. Without any common measure of value each trader would have to remember the value ratio between each article and all others offered in trade. Thus if he dealt in ten commodities he must remember forty-five ratios of exchange, but with a standard of value only nine ratios would be involved.