Until the last great war, a general expectation of material improvement was an idea peculiar to Western man. Now war and its aftermath have made economic and social progress a political imperative in every quarter of the globe. If we ignore this, there will be no peace. There has been a widening of horizons to which in the West we have been perhaps too insensitive. Yet it is as important as the extension of our vision into outer space.
Today continuing poverty and distress are a deeper and more important cause of international tensions, of the conditions that can produce war, than previously.

The Four Faces of Peace (1957)