In abbreviated form, by a kind of symbol, only the most essential information is passed on and passed on only to those concerned. It is more than a metaphor to describe the price system as a kind of machinery for registering change, or a system of telecommunications which enables individual producers to watch merely the movement of a few pointers, as an engineer might watch the hands of a few dials, in order to adjust their activities to changes of which they may never know more than is reflected in the price movement.

About a decade ago, at the request of Psychology Today magazine, I had an amusing debate with Richard Dawkins about testicles. Dawkins had famously proposed the metaphor of the “selfish gene” to explain how traits in organisms can be understood from the imagined point of view of a gene wishing to propagate itself. The underlying logic of the metaphor is compelling, yet it doesn't always seem to work gracefully—as in the case of human male genitalia.

The site of human testicles seems a bizarre anomaly from an evolutionary point of view, like positioning the driver of an armored vehicle in a sack strapped to the bumper. If the whole point of the human organism is to pass on genes, why put the repository of those precious genes out front, in harm's way?