Henry George
The Science of Political Economy
Book V, Money -- The Medium Of Exchange and Measure of Value

Introduction

This Book is really in the nature of a supplement to Book II, "The Nature of Wealth." In my first draft of arrangement, a matter of much perplexity, the discussion of money was to have followed the discussion of value, with which it is so intimately connected; or at least, to have followed the discussion as to the definition of wealth. But to have given to the subject of money in Book II the thorough treatment which present confusions seem to require would not only have disproportionately expanded that Book, but would have made needful the anticipation of some of the conclusions more logically and conveniently reached in Book III and Book IV I therefore finally determined as the best arrangement for the reader of this work to answer briefly in the last chapter of Book II the question as to the relation of money to wealth which the conclusion of the discussion of the nature of wealth would be certain to bring, and to defer a fuller discussion of the subject of money until after the production and distribution of wealth had both been treated. This point has now been reached, and continuing as it were Chapter XXI of Book II, "The Nature of Wealth," I proceed to the discussion of the medium of exchange and measure of value.