F or a decade after the bursting of the debt bubble in 1837, business conditions were depressed in the United States. The number of banks available for financing speculative adventures declined. Then, after another 10 years, public memory faded again.

In any case, during the same month reassurance came from still higher authority. Andrew W. Mellon said, “There is no cause for worry. The high tide of prosperity will continue.” Mr. Mellon did not know. Neither did any of the other public figures who then, as since, made similar statements. These are not forecasts; it is not to be supposed that the men who make them are privileged to look farther into the future than the rest. Mr. Mellon was participating in a ritual which, in our society, is thought to be of great value for influencing the course of the business cycle. By affirming solemnly that prosperity will continue, it is believed, one can help insure that prosperity will in fact continue. Especially among businessmen the faith in the efficiency of such incantation is very great.

Faced with the choice between changing one's mind and proving that there is no need to do so, almost everybody gets busy on the proof.