between duty and expediency, which is a prominent feature of the Kantian ethics. Methods of expediency, omitting all reference to the pure practical reason, can only bring about re-arrangements of circumstances in the mechanical course of nature. They can never guarantee the attainment of their end: they can never make it more than a speculative ideal, which may or may not be practicable. But if the end can be shown to be a duty, we have, from Kant’s point of view, the only reasonable ground for a conviction that it is realisable. We cannot, indeed, theoretically _know_ that it is realisable. “Reason is not sufficiently enlightened to survey the series of predetermining causes which would make it possible for us to predict with certainty the good or bad results of human action, as they follow from the mechanical laws of nature; although we may hope that things will turn out as we should desire” (p. 163). On the other hand, since the idea of perpetual peace is a moral ideal, an “idea of duty”, we are entitled to believe that it is practicable. “Nature guarantees the coming of perpetual peace, through the natural course of human propensities; not indeed with sufficient certainty to enable us to prophesy the future of this ideal theoretically, but yet clearly enough for practical purposes” (p. 157). One might extend this discussion indefinitely; but what has been said may suffice for general guidance. The “wise and sagacious” thought of Kant is not expressed in a simple style, and the translation has consequently been a very difficult piece of work. But the translator has shown great skill in manipulating the involutions, parentheses and prodigious sentences of the original. In this she has had the valuable help of Mr. David Morrison, M.A., who revised the whole translation with the greatest care and to whom she owes the solution of a number of difficulties. Her work will have its fitting reward if it succeeds in familiarising the English-speaking student of politics with a political essay of enduring value, written by one of the master thinkers of modern times. R. LATTA. _University of Glasgow_, May 1903. CONTENTS PAGE PREFACE BY PROFESSOR LATTA v TRANSLATOR’S INTRODUCTION 1 PERPETUAL PEACE 106 FIRST SECTION CONTAINING THE PRELIMINARY ARTICLES OF PERPETUAL PEACE BETWEEN STATES 107 SECOND SECTION CONTAINING THE DEFINITIVE ARTICLES OF PERPETUAL PEACE BETWEEN STATES 117 FIRST SUPPLEMENT CONCERNING THE GUARANTEE OF PERPETUAL PEACE 143 SECOND SUPPLEMENT—A SECRET ARTICLE FOR PERPETUAL PEACE 158