But when gold is a mere medium of exchange,--its chief use,--then it has only a conventional value; I mean, it does not make a nation rich or poor, since the rarer it is the more it will purchase of the necessaries of life. A pound's weight of gold, in ancient Greece, or in Mediaeval Europe, would purchase as much wheat as twenty pounds' weight will purchase to-day. If the mines of Mexico or Peru or California had never been worked, the gold in the civilized world three hundred years ago would have been as valuable for banking purposes, or as an exchange for agricultural products, as twenty times its present quantity, since it would have bought as much as twenty times the quantity will buy to-day. Make diamonds as plenty as crystals, they would be worth no more than crystals, if they were not harder and more beautiful. Make gold as plenty as silver, it would be worth no more than silver, except for manufacturing purposes; it would be worth no more to bankers and merchants. The vast increase in the production of the precious metals simply increased the value of the commodities for which they were exchanged. A laborer can purchase no more bread with a dollar to-day than he could with five cents three hundred years ago. Five cents were really as much wealth three hundred years ago as a dollar is to-day. Wherein, then, has the increase in the precious metals added to the wealth of the world, if a twentieth part of the gold and silver now in circulation would buy as much land, or furniture, or wheat, or oil three hundred years ago as the whole amount now used as money will buy to-day? Had no gold or silver mines been discovered in America, the gold and silver would have appreciated in value in proportion to the wear of them. In other words, the scarcer the gold and silver the more the same will purchase of the fruits of human industry. So industry is the wealth, not the gold. It is the cultivated farms and the manufactures and the buildings and the internal improvements of a country which constitute its real wealth, since these represent its industry,--the labor of men. Mines, indeed, employ the labor of men, but they do not furnish food for the body, or raiment to wear, or houses to live in, or fuel for cooking, or any purpose whatever of human comfort or necessity,--only a material for ornament; which I grant is wealth, so far as ornament is for the welfare of man. The marbles of ancient Greece were very valuable for the labor expended on them, either for architecture or for ornament. Gold and silver were early selected as useful and convenient articles for exchange, like bank-notes, and so far have inherent value as they supply that necessity; but if a fourth part of the gold and silver in existence would supply that necessity, the remaining three-fourths are as inherently valueless as the paper of which bank-notes are printed. Their value consists in what they represent of the labors and industries of men.