Two methods of indicating the presence of a French element in Alsace-Lorraine are given in the accompanying map (Pl. II) of this region. The method of showing percentages according to administrative districts[37] has been contrasted with the plan of representing the actual extension of French predominance.[38] In one respect the map is illuminating. It shows the concordance of French and German authorities regarding the German character of the language spoken in Alsace, as well as the French nature of a substantial portion of Lorraine. The Rhine valley, a natural region, appears throughout as an area of German speech. The startling preference of Alsatians for French nationality cannot therefore be substantiated by geographical evidence. It suggests the persistent influence of the human will swayed by feelings of justice and moral affinity rather than by material considerations. To primitive societies, a river as large as the Rhine provided almost as impassable a frontier as the sea itself. It had the advantage of being defined by nature. The boundary was actually marked on the ground. As frontiers of the Roman Empire, the Rhine and the Danube proved their practical value by the long period during which they marked the extent of imperial or republican domain. The history of oversea colonization indicates the partiality of colonial powers for rivers as boundaries. It is likely that in the very early period of man’s habitation of the earth, the tribes settled on either side of watercourses had little or no intercourse. As they advanced in civilization relations were developed. The divisive influence of running waters was therefore exerted most strongly at the dawn of human history. Later the river may become a link and finally may attain the stage when it is a rallying line for the activity and thought of the inhabitants of its entire valley. [Illustration: _The American Geographical Society of New York_ _Frontiers of Language and Nationality in Europe, 1917, Pl. II_ THE FRANCO-GERMAN LINGUISTIC BOUNDARY IN ALSACE-LORRAINE]