OPEN COURT and the above logo are registered in the U.S. Patent & Trademark Office.

Published 1985 by Open Court Publishing Company, Peru, Illinois 61354.

This edition first published 1951 by Routledge & Kegan Paul Limited, London.

Second printing 1988

Third printing 1990

Fourth printing 1993

Fifth printing 1996

Printed and bound in the United States of America.

Library of Congress Cataloging-in-Publication Data