Laughs with Ludwig

Once during a speech he was making at a statistical congress in Bern, Pareto spoke of 'natural economic laws,' whereupon [Gustav] Schmoller, who was present, said that there was no such thing. Pareto said nothing, but smiled and bowed. Afterwards he asked Schmoller, through one of his neighbors, whether he was well acquainted with Bern. When Schmoller said yes, Pareto asked him again whether he knew of an inn where one could eat for nothing. The elegant Schmoller is supposed to have looked half pityingly and half disdainfullly at the modestly dressed Pareto - although he was known to be well off - and to have answered that there were plenty of cheap restaurants, but that one had to pay something everywhere. At which Pareto said: 'So there are natural laws of political economy!'

An anecdote which Ludwig von Mises was fond of, related by Murray Rothbard in this book.