Aristotle, the Greek philosopher, summed up the four chief qualities of money some 2,000 years ago. It must be lasting and easy to recognize, to divide, and to carry about. In other words it must be, "durable, distinct, divisible and portable". When we think of money today, we picture it either as round, flat pieces of metal which we call coins, or as printed paper notes. But there are still parts of the world today where coins and notes are of no use. They will buy nothing, and a traveler might starve if he had none of the particular local "money" to exchange for food.

　　Among isolated peoples, who are not often reached by traders from outside, commerce usually means barter. There is a direct exchange of goods. For this kind of simple trading, money is not needed, but there is often something that everyone wants and everybody can use, such as salt to flavor food, shells for ornaments, or iron and copper to make into tools and vessels.
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　　These things-salt, shells or metals-are still used as money in out-of-the-way parts of the world today.

　　Salt may seem rather a strange substance to use as money, but in countries where the food of the people is mainly vegetable, it is often an absolute necessity. Cakes of salt, stamped to show their value, were used as money in Tibet until recent times, and cakes of salt will still buy goods in Borneo and parts of Africa.

　　Cowrie sea shells have been used as money at some time or another over the greater part of the Old World. These were collected mainly from the beaches of the Maldive Islands in the Indian Ocean, and were traded to India and China. In Africa, cowries were traded right across the continent from East to West. Four or five thousand went for one Maria Theresa dollar, an Austrian silver coin which was once accepted as money in many parts of Africa.

　　Metal, valued by weight, preceded coins in many parts of the world. Iron, in lumps, bars or rings, is still used in many countries instead of money. It can either be exchanged for goods, or made into tools, weapons or ornaments. The early money of China, apart from shell, was of bronze, often in flat, round pieces with a hole in the middle, called "cash". The earliest of these are between three thousand and four thousand years old-older than the earliest coins of the eastern Mediterranean.

　　Nowadays, coins and notes have replaced nearly all the more picturesque forms of money, and although in one or two of the more remote countries people still hold it for future use on ceremonial occasions such as weddings and funerals, examples of primitive money will soon be found only in museums.