At present I am working through various works of Ludwig von Mises, and eagerly awaiting the re-issue of Marchamont Nedham's "The Excellencie of a Free State: Or the Right Constitution for a Commonwealth". ('tho he were born in a cursed place' said Thompson)
This quote is from von Mises' "Theory of Money and Credit", from a short passage added to the 1922 edition, dealing with a criticism levelled at the first edition of 1912. I won't try to explain what the point was, but it's a good example of Mises' duelling style.
From the end of chapter 8.
The sort of procedure that Professor Lotz adopts here for solving a problem of economic science must necessarily end in failure. It is not enough to collect the opinions of businessmen—even if they are “leading” men or belong to “leading” houses—and then serve them up to the public, garnished with a few on the one hand’s and on the other hand’s, an admittedly or so, and a sprinkling of all the same’s. The collection of “facts” is not science, by a long way. There are no grounds for ascribing authoritative significance to the opinions of businessmen; for economics, these opinions are nothing more than material, to be worked upon and evaluated. When the businessman tries to explain anything he becomes as much a “theorist” as anybody else; and there is no reason for giving a preference to the theories of the practical merchant or farmer. It is, for instance, impossible to prove the cost-of-production theory of the older school by invoking the innumerable assertions of businessmen that “explain” variations in prices by variations in costs of production.
Nowadays there are many who, busied with the otiose accumulation of material, have lost their understanding for the specifically economic in the statement and solution of problems. It is high time to remember that economics is something other than the work of the reporter whose business it is to ask X the banker and Y the commercial magnate what they think of the economic situation.