Money

From The Joyless Economy:

When profits or earnings are all a man has to show for his work, he transfers to them his pride of achievement and regards them as the symbol and measure of society's appreciation of what he does for society. Such was the interpretation the Puritan ethic put on money income, and it has been reinforced by the economist's theory of the competitive market, which holds that the market price of a man's services reflects the value of his marginal contribution to the national product. We use money not only as a medium of exchange, but also as the measuring rod of a man's worth, and we value income not only for the goods it will buy, but also as the proof of our usefulness to society. Being useful to society is a source of satisfaction and comfort; money is a token of such usefulness and therefore becomes itself a source of satisfaction and comfort.