In this book Don Sturzo, the famous Italian Populist leader, now living in exile, shows himself quite as vigorous in the field of thought as he formerly showed himself in the field of action. He is not concerned here with the possible ways and means of organizing the world for peace, or yet with the problem of practical disarmament, but rather with the philosophical question whether war is a necessity. The viewpoint is pronouncedly Christian and Catholic, and the argument is presented with the dialectical power of the schoolman. Don Sturzo finds no difficulty in disposing of the usual arguments advanced in favor of war as an instrument of justice, as a necessary attribute of state power, or as a purely biological factor, and comes to the conclusion that the idea of the necessity of war is a pure illusion. It is inextricably bound up with the form of social organization, and therefore there can be nothing inevitable or eternal about it. As the social system changes and the tendency towards international organization replaces the purely national system, the ideas of moral constraint will inevitably prevail over the ideas of force.