53 2 THE AMERICAN JOURNAL OF SOCIOLOGY
had left a strong imprint upon their former lineaments, but which, in an organization generally issued from conquest, had persisted above all in their most rigid and most fixed aspect, the military aspect. The military and political frontiers, properly speaking, in harmony with the sovereignty generally survive with their primitive character, at the time when the limits of the other social forces, very much less stable by reason of their special nature and complexity, such as art, religion, morals, law, and even those of economic life, for a long time have exceeded the strategic frontiers by which the public authority is officially and nominally circum- scribed. The inverse phenomena, however, may happen, and the political authority may embrace within its limits a domain and a population of which certain parts are in reality already removed from its influence and may gravitate within the sphere of external centers. Then, sooner or later, a displacement of the political frontiers will be inevitable for the sake of an effective equilibrium of the intersocial forces.
Let us remark that this great Egyptian civilization was extended over the two banks of the Nile, just as other civilizations were developed on the banks of the Tigris and Euphrates. These rivers of the most remote antiquity were no more barriers than if they had never existed. They were means of communication; and similarly the little principalities prior to the foundation of the great empires were not limited by the creeks, which also generally irrigated, like the great rivers, homogeneous populations scattered along the two banks. Only during a certain period of time did the seas and deserts, especially the latter, serve as obstacles, as physical limits. From 5000 to about 3000 B. C, under the first Pharaohs, Egypt was inclosed within physical limits at the north, east, and west by sea and desert. Under the Fourth Dynasty the Pharaohs installed themselves along the Red Sea and also along the opposite shores of the gulf which extends up to the Isthmus of Suez. The deserts were crossed at the latter place. The oases of the west were occupied only after the close of the Sixth Dynasty, and it was only after the Thirteenth Dynasty that Egypt extended above the second cataract. Then it crossed the isthmus, and in the time of Amenophis III it came in contact with
