This is, I think, the only complete translation into English of Kant’s essay, including all the notes as well as the text, and the translator has added a full historical Introduction, along with numerous notes of her own, so as (in Professor Ritchie’s words) “to meet the needs (1) of the student of Political Science who wishes to understand the relation of Kant’s theories to those of Grotius, Hobbes, Locke, Rousseau etc., and (2) of the general reader who wishes to understand the significance of Kant’s proposals in connection with the ideals of Peace Congresses, and with the development of International Law from the end of the Middle Ages to the Hague Conference.” Although it is more than 100 years since Kant’s essay was written, its substantial value is practically unimpaired. Anyone who is acquainted with the general character of the mind of Kant will expect to find in him sound common-sense, clear recognition of the essential facts of the case and a remarkable power of analytically exhibiting the conditions on which the facts necessarily depend. These characteristics are manifest in the essay on _Perpetual Peace_. Kant is not pessimist enough to believe that a perpetual peace is an unrealisable dream or a consummation devoutly to be feared, nor is he optimist enough to fancy that it is an ideal which could easily be realised if men would but turn their hearts to one another. For Kant perpetual peace is an ideal, not merely as a speculative Utopian idea, with which in fancy we may play, but as a moral principle, which ought to be, and therefore can be, realised. Yet he makes it perfectly clear that we cannot hope to approach the realisation of it unless we honestly face political facts and get a firm grasp of the indispensable conditions of a lasting peace. To strive after the ideal in contempt or in ignorance of these conditions is a labour that must inevitably be either fruitless or destructive of its own ends. Thus Kant demonstrates the hopelessness of any attempt to secure perpetual peace between independent nations. Such nations may make treaties; but these are binding only for so long as it is not to the interest of either party to denounce them. To enforce them is impossible while the nations remain independent. “There is,” as Professor Ritchie put it (_Studies in Political and Social Ethics_, p. 169), “only one way in which war between independent nations can be prevented; and that is by the nations ceasing to be independent.” But this does not necessarily mean the establishment of a despotism, whether autocratic or democratic. On the other hand, Kant maintains that just as peace between individuals within a state can only be permanently secured by the institution of a “republican” (that is to say, a representative) government, so the only real guarantee of a permanent peace between nations is the establishment of a federation of free “republican” states. Such a federation he regards as practically possible.