Let us never forget this: since the day of the air, the old frontiers are gone. When you think of the defense of England you no longer think of the chalk cliffs of Dover; you think of the Rhine. That is where our frontier lies. ↗
In particular, the efforts to reestablish peace after the World War have been directed toward the formation of states and the regulation of their frontiers according to a consciously national program. ↗
Since the day of the air, the old frontiers are gone. When you think of the defense of England you no longer think of the chalk cliffs of Dover; you think of the Rhine. ↗
Modern techniques have torn down state frontiers, both economical and intellectual. The growth of means of transport has created a world market and an opportunity for division of labor embracing all the developed and most of the undeveloped states. ↗