During early centuries in the history of western civilization adventurers and prospectors concentrated on the precious metals. The voyagers and discoverers who sailed fifteenth century seas were seeking supplies of gold, silver and precious stones that could be cut and converted into the highly prized jewels adorning the crowns and scepters of the mighty. Production at that stage meant agriculture, with side occupations such as hunting, fishing, weaving, tanning, pottery, thatching and peat cutting, in the all but continuous countryside. There was a very little mining, but outside of the commercial towns and the growing capital cities people made their living by taking care of domestic animals and tilling the soil. Between seed time and harvest they tightened their belts and prayed the Powers that Be for a bountiful yield. If it came they feasted. If the crop failed they struggled to survive on the narrow margin between hunger and starvation. If they saw any money it was likely to be copper, with perhaps an occasional piece of silver. Gold was for the rich, of whom at that period there were precious few, even among the owners of land and the wielders of power. Country folk barely scratched the surface of the earth. Roads were wheel tracks in the mud. Bridges were fords that became more or less impassable with high water. These assertions sound strange and romantic to the modern beneficiaries of asphalt and reinforced concrete. They were the lot of most Europeans and North Americans when our great grandfathers and great grandmothers were in their prime. What has made the difference between their use of the earth and ours? Chiefly, the newly tapped sources of energy and the wide variety of minerals--whose names were unknown except to scholars and scientists before 1750. It is the new sources of energy and the only recently utilized metals that have made the difference. Farm land can be used and abused many times before its productive possibilities are exhausted. Even then, with foresight, technical proficiency, the investment of labor and capital, agricultural land can be restored to fertility. Iron ore, tin, copper and tungsten are extracted from the earth, refined, put to some use or wasted as the case may be, but they are gone. They may be replaced by other minerals. Through geological ages they may redeposited in the earth's crust. But to all intents and purposes, they are finished. It is a source of pride to promoters and propagandists for the status quo that western man has removed more metals and minerals from the earth's crust in the past two hundred years than his predecessors removed during the previous two thousand years. It is also a source of danger, because the possibilities of taking those particular minerals from that particular cubic foot of the earth are ended.