"Professor Fisher's The Purchasing Power of Money is dedicated to Simon Newcomb, from whom vid Professor Kemmerer the PT = MV formula ultimately derives. Newcomb was not a professional economist but a mathematician (Professor of Mathematics in the U.S. Navy and at Johns Hopkins). His Principles of Political Economy, published in 1886, is one of those original works which a fresh scientific mind, not perverted by having read too much of the orthodox stuff, is able to produce from time to time in a half -formed subject like economics."