Marx did do original work in analyzing patterns of circular inter-dependency among industries. Such work gains few converts and is not very helpful i… - Paul Samuelson

In the absence of perfect certainty, the futures prices needed for making the requisite wealth-like comparisons are simply unavailable. So it would be difficult to make operational the theorist’s desired measures. But operational practicality aside, if the theorist specifies in detail the dynamic technology of his model, he will meet none of the pitfalls that come from an attempt to summarize his model by various crude aggregations. The contradictions that result from over-crude aggregation should never be confused with the technical relations that hold at the firm and family level or with the market capitalizations which hold in competitive security and asset markets.

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 is merely a child grown large. Man is imperfect, and so is woman. And so is We, Incorporated, who paternalistically put restraints upon ourselves. Not even an individual's perfections are his alone; like his imperfections, they are group-made. We entered a world we never made, and leave one we did not unmake.

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.