In his bitter and vigorous reply to Misselden's Circle of Commerce , Malynes, one of the foremost bullionists, maintained that the "center" was gain, not the balance of trade whose usefulness he questioned by doubting the reliability of estimates that purported to measure it. "This criticism was by no means unjustified, and subsequent writers often conceded the grounds on which it was based." H.W. Spiegel The Growth of Economic Thought