In every actuarial situation of mathematical probability, no matter how large the numbers in the sample, we are left with a finite sample: in the app… - Paul Samuelson

The recent market run-up that appreciated run-of-the-mill shares also chanced to send up those token gold holdings. Pure luck, undeserved and unlikely to reoccur. Good questions outrank easy answers.

I reproach myself for a gross error. But I would reproach myself more if I had persisted in an error after observations revealed it clearly to be that. I made a deal of money in the late 1940s on the bull side, ignoring Satchel Paige’s advice to Lot’s wife, “Never look back.” Rather I would advocate Samuelson’s Law: “Always look back. You may learn something from your residuals. Usually one’s forecasts are not so good as one remembers them; the difference may be instructive.” The dictum “If you must forecast, forecast often,” is neither a joke nor a confession of impotence. It is a recognition of the primacy of brute fact over pretty theory. That part of the future that cannot be related to the present’s past is precisely what science cannot hope to capture. Fortunately, there is plenty of work for science to do, plenty of scientific tasks not yet done.

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.