For some time after the first discovery of America, silver would continue to sell at its former, or not much below its former price. The profits of mining would for some time be very great, and much above their natural rate. Those who imported that metal into Europe, however, would soon find that the whole annual importation could not be disposed of at this high price. Silver would gradually exchange for a smaller and a smaller quantity of goods. Its price would sink gradually lower and lower, till it fell to its natural price; or to what was just sufficient to pay, according to their natural rates, the wages of the labour, the profits of the stock, and the rent of the land, which must be paid in order to bring it from the mine to the market. In the greater part of the silver mines of Peru, the tax of the king of Spain, amounting to a tenth of the gross produce, eats up, it has already been observed, the whole rent of the land. This tax was originally a half; it soon afterwards fell to a third, then to a fifth, and at last to a tenth, at which rate it still continues. In the greater part of the silver mines of Peru, this, it seems, is all that remains, after replacing the stock of the undertaker of the work, together with its ordinary profits; and it seems to be universally acknowledged that these profits, which were once very high, are now as low as they can well be, consistently with carrying on the works. The tax of the king of Spain was reduced to a fifth of the registered silver in 1504[19], one-and-forty years before 1545, the date of the the discovery of the mines of Potosi. In the course of ninety years, or before 1636, these mines, the most fertile in all America, had time sufficient to produce their full effect, or to reduce the value of silver in the European market as low as it could well fall, while it continued to pay this tax to the king of Spain. Ninety years is time sufficient to reduce any commodity, of which there is no monopoly, to its natural price, or to the lowest price at which, while it pays a particular tax, it can continue to be sold for any considerable time together. The price of silver in the European market might, perhaps, have fallen still lower, and it might have become necessary either to reduce the tax upon it, not only to one-tenth, as in 1736, but to one twentieth, in the same manner as that upon gold, or to give up working the greater part of the American mines which are now wrought. The gradual increase of the demand for silver, or the gradual enlargement of the market for the produce of the silver mines of America, is probably the cause which has prevented this from happening, and which has not only kept up the value of silver in the European market, but has perhaps even raised it somewhat higher than it was about the middle of the last century. Since the first discovery of America, the market for the produce of its silver mines has been growing gradually more and more extensive.