Before Rousseau, people made the mistake of treating children as merely adults shrunk small. The Bible and Freud go farther and tell us that an adult… - Paul Samuelson

There is really nothing more pathetic than to have an economist or a retired engineer try to force analogies between the concepts of physics and the concepts of economics. How many dreary papers have I had to referee in which the author is looking for something that corresponds to entropy or to one or another form of energy. Nonsensical laws, such as the law of conservation of purchasing power, represent spurious social science imitations of the important physical law of the conservation of energy; and when an economist makes reference to a Heisenberg Principle of indeterminacy in the social world, at best this must be regarded as a figure of speech or a play on words, rather than a valid application of the relations of quantum mechanics.

With the assistance of mathematics, I can see a property of the ninety-nine dimensional surfaces hidden from the naked eye. If an increase in the price of fertilizer alone always increases the amount the firm buys of caviar, from that fact alone I can predict the answer to the following experiment which I have never seen performed and upon which I have no observations: an increase in the price of caviar alone will increase the amount the firm buys of fertilizer. In thermodynamics such reciprocity or integrability conditions are known as Maxwell Conditions; in economics they are known as Hotelling conditions in honor of Harold Hotelling’s 1932 work.

I can claim that in talking about modern economics I am talking about me. My finger has been in every pie. I once claimed to be the last generalist in economics, writing about and teaching such diverse subjects as international trade and econometrics, economic theory and business cycles, demography and labor economics, finance and monopolistic competition, history of doctrines and locational economics.