Professor Carr is the author of Conditions of Peace. This is a further analysis, in essay form, of the forces of nationalism and internationalism as they have shaped the past, as they jeopardize the future. Succinctly he surveys the three eras of nationalism with the character of the nation state in each, the changes which took place, with the second world war as climax and catastrophe of the third period. Internationalism, he believes, is dependent on the balance between idealism and power. He outlines briefly the mechanics, principles and purposes of internationalism -- the factors which militate against it. This is by no means easy reading; it is however an important recapitulation as well as a springboard for future action. It will probably be limited to students, experts, international authorities interested in general theory.