February revolution and my expulsion from Belgium which followed it as a consequence. The publication of the “Neue Rheinische Zeitung” in 1848 and 1849, and the events which took place later on, interrupted my economic studies which I could not resume before 1850 in London. The enormous material on the history of political economy which is accumulated in the British Museum; the favorable view which London offers for the observation of bourgeois society; finally, the new stage of development upon which the latter seemed to have entered with the discovery of gold in California and Australia, led me to the decision to resume my studies from the very beginning and work up critically the new material. These studies partly led to what might seem side questions, over which I nevertheless had to stop for longer or shorter periods of time. Especially was the time at my disposal cut down by the imperative necessity of working for a living. My work as contributor on the leading Anglo-American newspaper, the “New York Tribune,” at which I have now been engaged for eight years, has caused very great interruption in my studies, since I engage in newspaper work proper only occasionally. Yet articles on important economic events in England and on the continent have formed so large a part of my contributions that I have been obliged to make myself familiar with practical details which lie outside the proper sphere of political economy. This account of the course of my studies in political economy is simply to prove that my views, whatever one may think of them, and no matter how little they agree with the interested prejudices of the ruling classes, are the result of many years of conscientious research. At the entrance to science, however, the same requirement must be put as at the entrance to hell: Qui si convien lasciare ogni sospetto Ogni viltà convien che qui sia morta. Karl Marx. London, January, 1859. CONTENTS. PAGE. Translator’s Preface 3 Author’s Preface 9 BOOK I. CAPITAL IN GENERAL. Chapter I. Commodities 19 A. Notes on the History of the Theory of Value 56 Chapter II. Money or Simple Circulation 73 1. The Measure of Value 74 B. Theories of the Unit of Measure of Money 91 2. The Medium of Circulation 107 a. The Metamorphosis of Commodities 108 b. The Circulation of Money 125 c. Coin and Symbols of Value 138 3. Money 162