INTRODUCTION TO SOCIOLOGY 71
directly attached to it than central and occidental Europe. In the year 395 the empire is divided, and there are two prefects in each of its two parts. The division of the central power of necessity increased parallel with the shifting of frontiers and the internal social transformation. Under the later empire the principle of separating military and civic functions is to prevail. There will be masters of the forces, and under them counts and dukes whose prerogatives extend over regions of various size, sometimes including several provinces. Instead of being concentrated, the troops are dispersed in garrisons of various sizes along the Rhine and the Danube from source to mouth. Danger threatens every- where from without, and society is in full transformation within. New conditions must necessarily have as a result a transforma- tion of the frontiers. The dissolution of the empire goes on parallel with the social reorganization of its content, in connection with the internal and external conditions of the latter.
Religious and philosophical beliefs were in continuous correla- tion with the evolution already passed through, and with that which was in progress.
Just as the fosse around the primitive towns was the mundus, at first the strictly inviolable circle of social life, so under the empire the " Roman world," including its most distant extremi- ties, was such a life-circle. At its boundaries all social assimila- tion ceased to be possible. However great the Roman city became, whatever was its force of expansion, it was always limited. At its apogee as at the beginning, its limitations are very rigid. It has a belt of strong castles and of military colonies wherever physical obstacles do not afford sufficient means of defense. In fact, there is so little confidence in the latter that at the approach of danger military posts are scattered all along the frontier, even where there are large rivers and high mountains.
In the midst of this world, so broad that to the eyes of the great mass of its inhabitants it might well have seemed limitless, a homogeneous social life developed itself progressively by the extension of the great routes of commerce ; by the necessity of a more and more intensive production, both agricultural and indus- trial; by the slow fusion of human varieties; by the fusion of usages of customs, of divinities, and even of philosophies; by
