"If a new map of Europe follows the war, its permanence will depend upon whether or not the changes are such as will permit nationalities to organize as nations. "The world should have learned through the lessons of the past that it is impossible permanently and peacefully to submerge large bodies of aliens if they are treated as aliens. That is the opposite of the mixing process which is so successfully building a nation out of varied nationalities in the United States. "The old Romans understood this. They permitted their outlying vassal nations to speak any language they chose and to worship whatever god they chose, so long as they recognized the sovereignty of Rome. When a conquering nation goes beyond that, and begins to suppress religions, languages, and customs, it begins at that very moment to sow the seeds of insurrection and revolution. "My old teacher and colleague, Prof. Burgess, once defined a nation as an ethnographic unit inhabiting a geographic unit. That is an illuminating definition. If a nation is not an ethnographic unit, it tries to become one by oppressing or amalgamating the weaker portions of its people. If it is not a geographic unit, it tries to become one by reaching out to a mountain chain or to the sea--to something which will serve as a real dividing line between it and its next neighbors. "The accuracy of this definition can hardly be denied, and we all know what the violations of this principle have been in Europe. It is unnecessary for me to point them out. "Races rarely have been successfully mixed by conquest. The military winner of a war is not always the real conqueror in the long run. The Normans conquered Saxon England, but Saxon law and Saxon institutions worked up through the new power and have dominated England's later history. The Teutonic tribes conquered Rome, but Roman civilization, by a sort of capillary attraction, went up into the mass above and presently dominated the Teutons. "The persistency of a civilization may well be superior in tenacity to mere military conquest and control. "The smallness of the number of instances in which conquering nations have been able successfully to deal with alien peoples is extraordinary. The Romans were unusually successful, and England has been successful with all but the Irish, but perhaps no other peoples have been successful in high degree in an effort to hold alien populations as vassals and to make them really happy and comfortable as such. "One of the war's chief effects on us will be to change our point of view. Europe will be more vivid to us from now on. There are many public men who have never thought much about Europe, and who have been far from a realization of its actual importance to us. It has been a place to which to go for a Summer holiday.