as the Ural Mountains, California, and Australia, may be the commencement of another period of decline, on the limits of which it would be useless at present to speculate. But, on the whole, no commodities are so little exposed to causes of variation. They fluctuate less than almost any other things in their cost of production. And, from their durability, the total quantity in existence is at all times so great in proportion to the annual supply, that the effect on value even of a change in the cost of production is not sudden: a very long time being required to diminish materially the quantity in existence, and even to increase it very greatly not being a rapid process. Gold and silver, therefore, are more fit than any other commodity to be the subject of engagements for receiving or paying a given quantity at some distant period.
When gold and silver had become virtually a medium of exchange, by becoming the things for which people generally