west, must needs take Orleans before they could enter the heart of the country. Finally, it was for the same reason that the English fought for the same city in 1429, and the Germans took it twice, in 1815 and again in 1870. This district, then, between Paris and Orleans, is the key to the geographical situation, because it lies at the middle point of this backbone of fertility from north to south.
The second axis, lying along the river Rhone, is of somewhat less importance as a center of population because of its extreme narrowness. Yet it is a highway of migration between the north and the south of Europe, skirting the Alps; and it is easily accessible to the people of the Seine basin by the low plateau of Langres near the city of Dijon. This renders it the main artery of communication from Paris to the Mediterranean. Down its course Teutonic blood has flowed. The culture of the south has spread into northern Europe in the contrary direction. Such is the normal exchange between the two climates in human history, the world over. The great fertility of the Rhone axis, moreover, is in strong contrast to the character of the country upon either side. Judged by its population, it merits the important position we have here assigned to it.
These two axes of fertility divide France, as we have said, into three areas which exhibit the phenomena of social isolation in different degrees. East of the Rhone lies Savoy, exceedingly mountainous, with a rigorous Alpine climate, and of a geological formation yielding with difficulty to cultivation. This region combines two safeguards against ethnic invasion. In the first place, it is not economically attractive; for the colonist is unmoved by those charms which appeal to the tourist to-day. We reiterate, the movement of peoples is dependent upon the immediate prosperity of the country for them. It matters not whether the invading hosts be colonists, coming for permanent settlement, or barbarians in search of booty; the result is the same in either case. Savoy, therefore, has seldom attracted the foreigner. It could not offer him a livelihood if he came. In the second place, whenever threatened with invasion, the defense of the country was easy. Permanent conquest is impossible in so mountainous a district. Combining both of these safeguards in an extreme degree. Savoy, therefore, offers some of the most remarkable examples of social individuality in all France.
The second area of isolation lies between our two north and south axes of fertility—that is to say, between the Rhone on the east and the Garonne on the southwest. It centers in the ancient province of Auvergne, known geographically as the Massif Centrale. This comprises only a little less than two thirds of France south of Dijon. In reality it is an outpost of the Alps cut off
