"We may not appreciate the fact; but a fact nevertheless it remains: we are living in a Golden Age, the most gilded Golden Age of human history — not only of past history, but of future history. For, as Sir Charles Darwin and many others before him have pointed out, we are living like drunken sailors, like the irresponsible heirs of a millionaire uncle. At an ever accelerating rate we are now squandering the capital of metallic ores and fossil fuels accumulated in the earth's crust during hundreds of millions of years. How long can this spending spree go on? Estimates vary. But all are agreed that within a few centuries or at most a few millennia, Man will have run through his capital and will be compelled to live, for the remaining nine thousand nine hundred and seventy or eighty centuries of his career as Homo sapiens, strictly on income. Sir Charles is of the opinion that Man will successfully make the transition from rich ores to poor ores and even sea water, from coal, oil, uranium and thorium to solar energy and alcohol derived from plants. About as much energy as is now available can be derived from the new sources — but with a far greater expense in man hours, a much larger capital investment in machinery. And the same holds true of the raw materials on which industrial civilization depends. By doing a great deal more work than they are doing now, men will contrive to extract the diluted dregs of the planet's metallic wealth or will fabricate non-metallic substitutes for the elements they have completely used up. In such an event, some human beings will still live fairly well, but not in the style to which we, the squanderers of planetary capital, are accustomed."