Copyright © 1971, 2004 by Princeton University Press
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In the United Kingdom: Princeton University Press,
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All Rights Reserved

First edition, 1971

150th Anniversary Edition, 2004

Princeton Classics Edition, 2016

Paperback ISBN: 978-0-691-16934-7

Library of Congress Control Number: 2015959717

British Library Cataloging-in-Publication Data is available

Printed on acid-free paper ∞

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Printed in the United States of America

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