Gold and silver are not by nature money, but money consists by its nature of gold and silver. The universal product of the social process, or the social process itself considered as a product, is a particular natural product, a metal, which is contained in the earth's crust and can be dug up. Their value is nevertheless more stable than that of other commodities on the average, as even Aristotle noted. Apart from the general effect of an appreciation or depreciation of the precious metals, variations in the relative value of gold and silver are of particular importance, since both are used side by side as monetary material on the world market. This labour-time itself will depend on the relative scarcity of natural deposits and the difficulties involved in procuring them in a purely metallic state.
Gold is in fact the first metal that man discovered.
The value of silver is therefore originally higher than that of gold, although it is absolutely less scarce. Strabo's statement that an Arabian tribe gave ten pounds of gold for one pound of iron, and two pounds of gold for one pound of silver, is by no means incredible. But the value of silver tends to fall in relation to that of gold, as the productive powers of social labour develop and consequently the product of simple labour becomes more expensive compared with that of complex labour, and with the earth's crust being increasingly opened up the original surface-sources of gold are liable to be exhausted. Finally, at a given stage of development of technology and of the means of communication, the discovery of new territories containing gold or silver plays an important role. The working of the Spanish silver mines by Carthage and later by Rome exerted a rather similar influence on the ancient world to that of the discovery of the American mines on modern Europe.