The Wealth of Nations by Part 1 Chapter 11 Page 194

almost all consumed long before the end of this year. But some part of the iron which was brought from the mine two or three hundred years ago may be still in use, and perhaps some part of the gold which was brought from it two or three thousand years ago. The different masses of corn which in different years must supply the consumption of the world will always be nearly in proportion to the respective produce of those different years. But the proportion between the different masses of iron which may be in use in two different years will be very little affected by any accidental difference in the produce of the iron mines of those two years; and the proportion between the masses of gold will be still less affected by any such difference in the produce of the gold mines.

Though the produce of the greater part of metallic