As the price both of the precious metals and of the precious stones is regulated all over the world by their price at the most fertile mine in it, the rent which a mine of either can afford to its proprietor is in proportion, not to its absolute, but to what may be called its relative fertility, or to its superiority over other mines of the same kind. If new mines were discovered as much superior to those of Potosi as they were superior to those Europe, the value of silver might be so much degraded as to render even the mines of Potosi not worth the working. Before the discovery of the Spanish West Indies, the most fertile mines in Europe may have afforded as great a rent to their proprietor as the richest mines in Peru do at present. Though the quantity of silver was much less, it might have exchanged for an equal quantity of other goods, and the proprietor's share might have enabled him to purchase or command an equal quantity either of labour or of commodities. The value both of the produce and of the rent, the real revenue which they afforded both to the public and to the proprietor, might have been the same.
The most abundant mines either of the precious metals or of the precious stones could add little to the wealth of the world. A produce of which the value is principally derived from its scarcity, is necessarily degraded by its abundance. A service of plate, and the other frivolous ornaments of dress and furniture, could be purchased for a smaller quantity of labour, or for a smaller quantity of commodities; and in this would consist the sole advantage which the world could derive from that abundance.
It is otherwise in estates above ground. The value both of their produce and of their rent is in proportion to their absolute, and not to their relative fertility. The land which produces a certain quantity of food, clothes, and lodging, can always feed, clothe, and lodge a certain number of people; and whatever may be the proportion of the landlord, it will always give him a proportionable command of the labour of those people, and of the commodities with which that labour can supply him. The value of the most barren lands is not diminished by the neighbourhood of the most fertile. On the contrary, it is generally increased by it. The great number of people maintained by the fertile lands afford a market to many parts of the produce of the barren, which they could never have found among those whom their own produce could maintain.
Whatever increases the fertility of land in producing food increases not only the value of the lands upon which the improvement is bestowed, but contributes likewise to increase that of many other lands by creating a new demand for their produce. That abundance of food, of which, in consequence of the improvement of land, many people have the disposal beyond what they themselves can consume, is the great cause of the demand both for the precious metals and the precious stone, as well as for every other conveniency and ornament of dress, lodging, household furniture, and equipage. Food not only constitutes the principal part of the riches of the world, but it is the abundance of food which gives the principal part of their value to many other sorts of riches. The poor inhabitants of Cuba and St. Domingo, when they were first discovered by the Spaniards, used to wear little bits of gold as ornaments in their hair and other parts of their dress. They seemed to value them as we would do any little pebbles of somewhat more than ordinary beauty, and to consider them as just worth the picking up, but not worth the refusing to anybody who asked them. They gave them to their new guests at the first request, without seeming to think that they had made them any very valuable present. They were astonished to observe the rage of the Spaniards to obtain them; and had no notion that there could anywhere be a country in which many people had the disposal of so great a superfluity of food, so scanty always among themselves, that for a very small quantity of those glittering baubles they would willingly give as much as might maintain a whole family for many years. Could they have been made to understand this, the passion of the Spaniards would not have surprised them.
===Part 3: Of the Variations in the Proportion between the respective Values of that Sort of Produce which always affords Rent, and of that which sometimes does and sometimes does not afford Rent===
The increasing abundance of food, in consequence of increasing improvement and cultivation, must necessarily increase the demand for every part of the produce of land which is not food, and which can be applied either to use or to ornament. In the whole progress of improvement, it might therefore be expected, there should be only one variation in the comparative values of those two different sorts of produce. The value of that sort which sometimes does and sometimes does not afford rent, should constantly rise in proportion to that which always affords some rent. As art and industry advance, the materials of clothing and lodging, the useful fossils and minerals of the earth, the precious metals and the precious stones should gradually come to be more and more in demand, should gradually exchange for a greater and a greater quantity of food, or in other words, should gradually become dearer and dearer. This accordingly has been the case with most of these things upon most occasions, and would have been the case with all of them upon all occasions, if particular accidents had not upon some occasions increased the supply of some of them in a still greater proportion than the demand.
The value of a free-stone quarry, for example, will necessarily increase with the increasing improvement and population of the country round about it, especially if it should be the only one in the neighbourhood. But the value of a silver mine, even though there should not be another within a thousand miles of it, will not necessarily increase with the improvement of the country in which it is situated. The market for the produce of a freestone quarry can seldom extend more than a few miles round about it, and the demand must generally be in proportion to the improvement and population of that small district. But the market for the produce of a silver mine may extend over the whole known world. Unless the world in general, therefore, be advancing in improvement and population, the demand for silver might not be at all increased by the improvement even of a large country in the neighbourhood of the mine. Even though the world in general were improving, yet if, in the course of its improvement, new mines should be discovered, much more fertile than any which had been known before, though the demand for silver would necessarily increase, yet the supply might increase in so much a greater proportion that the real price of that metal might gradually fall; that is, any given quantity, a pound weight of it, for example, might gradually purchase or command a smaller and a smaller quantity of labour, or exchange for a smaller and a smaller quantity of corn, the principal part of the subsistence of the labourer.
The great market for silver is the commercial and civilised part of the world.
If by the general progress of improvement the demand of this market should increase, while at the same time the supply did not increase in the same proportion, the value of silver would gradually rise in proportion to that of corn. Any given quantity of silver would exchange for a greater and a greater quantity of corn; or, in other words, the average money price of corn would gradually become cheaper and cheaper.
If, on the contrary, the supply by some accident should increase for many years together in a greater proportion than the demand, that metal would gradually become cheaper and cheaper; or, in other words, the average money price of corn would, in spite of all improvements, gradually become dearer and dearer.
But if, on the other hand, the supply of the metal should increase nearly in the same proportion as the demand, it would continue to purchase or exchange for nearly the same quantity of corn, and the average money price of corn would, in spite of all improvements, continue very nearly the same.
These three seem to exhaust all the possible combinations of events which can happen in the progress of improvement; and during the course of the four centuries preceding the present, if we may judge by what has happened both in France and Great Britain, each of those three different combinations seem to have taken place in the European