By virtue of the law of conservation, all engines are necessarily 100 percent efficient. To say that an engine is less than perfectly efficient requires a normative judgment that separates the output into useful or desired output and waste. A pump that moves water uphill to a house can be said to be less than 100 percent efficient only as a result of someone’s having judged that such things as the water lost in transit and the heat dissipated in the pump house are unwanted and hence represent waste. It is the same with society. . . . The efficiency of an economy cannot be judged without placing some valuation upon different uses of time, any more than the efficiency of an engine can be judged without placing some valuation upon different transformations of energy.
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