The Empire covered itself with cities great and small, rivalling each other in splendour and wealth; and into these cities, at the expense of depopulating the countryside where nobody was willing any longer to live, it attracted the peasantry, the village artisans, and the yeomanry. In these cities, schools were opened in which the youth of the middle class were taught eloquence, literature, and philosophy, and trained for official posts, the number of which increased from generation to generation, and for the liberal professions. Thus, in the second century A.D., the Empire spread, in the sun of the _pax Romana_, which illumined the world, its countless marble-decked cities, as our time spreads, in the sun of modern civilisation, the confused and smoky opulence of its cities, large and moderate-sized, crowded, disordered, a blaze of light by night, bristling with chimneys and shrouded in black fog by day. In other words, the most important phenomenon in the whole history of the Roman Empire, during the first two centuries of the Christian era, is, as in the nineteenth century, the rapid growth and enrichment of the cities. The phenomenon was not then so rapid nor on so large a scale as it is to-day; not a single city in the Empire, not even Rome, ever attained, in my opinion, a population of one million inhabitants. The cities which seemed big in those days would be only of moderate size now. Populations and riches were smaller. But the phenomenon in itself was the same. From the third century onwards, the excessive urbanisation in the Roman Empire, which had been the cause of the splendour and apparent wealth of the preceding century, began to change into a dissolving force, which drove that brilliant world back into the chaos from which urbanisation had evolved it. Little by little, the expenditure of the urban civilisation, the cities and their increasing luxury, out-distanced the fertility of the countryside, and, from that moment, the latter began to be depopulated and sterilised by the cities. With each succeeding generation, the impulse towards the cities became stronger. The numbers and the requirements of the modern population increased. The State and the wealthy classes were inundated with requests, prayers, and threats, urging them to satisfy these requirements, to adorn and enrich ever more and more the cities, which were the glory and splendour of the Empire.