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 market, and nearly in the same order, too, in which I have here set them down.