But please do not be too sentimental about the "good old days." Many people who only see the beautiful churches and the great works of art which the Middle Ages have left behind grow quite eloquent when they compare our own ugly civilisation with its hurry and its noise and the evil smells of backfiring motor trucks with the cities of a thousand years ago. But these mediaeval churches were invariably surrounded by miserable hovels compared to which a modern tenement house stands forth as a luxurious palace. It is true that the noble Lancelot and the equally noble Parsifal, the pure young hero who went in search of the Holy Grail, were not bothered by the odor of gasoline. But there were other smells of the barnyard variety--odors of decaying refuse which had been thrown into the street--of pig-sties surrounding the Bishop's palace--of unwashed people who had inherited their coats and hats from their grandfathers and who had never learned the blessing of soap. I do not want to paint too unpleasant a picture. But when you read in the ancient chronicles that the King of France, looking out of the windows of his palace, fainted at the stench caused by the pigs rooting in the streets of Paris, when an ancient manuscript recounts a few details of an epidemic of the plague or of small-pox, then you begin to under-stand that "progress" is something more than a catchword used by modern advertising men. No, the progress of the last six hundred years would not have been possible without the existence of cities. I shall, therefore, have to make this chapter a little longer than many of the others. It is too important to be reduced to three or four pages, devoted to mere political events. The ancient world of Egypt and Babylonia and Assyria had been a world of cities. Greece had been a country of City-States. The history of Phoenicia was the history of two cities called Sidon and Tyre. The Roman Empire was the "hinterland" of a single town. Writing, art, science, astronomy, architecture, literature, the theatre--the list is endless--have all been products of the city. For almost four thousand years the wooden bee-hive which we call a town had been the workshop of the world. Then came the great migrations. The Roman Empire was destroyed. The cities were burned down and Europe once more became a land of pastures and little agricultural villages. During the Dark Ages the fields of civilisation had lain fallow. The Crusades had prepared the soil for a new crop. It was time for the harvest, but the fruit was plucked by the burghers of the free cities.