If the feeble and precarious commercial activity of the Carolingian period was sufficient to create gathering-places of merchants at the points most frequented in travel, it is not difficult to understand that the steady progress of economic activity from the end of the tenth century would result in the formation, at the strategic points of regional transit, of aggregations of like character but much more important and more stable. The surface of the land, the direction and the depth of the streams, determining the routes of commerce, also determined the location of the towns. Indeed, European cities are the daughters of commerce and of industry. Unquestionably in the countries of old civilization, in Italy or in Gaul, the Roman cities had not completely disappeared. Within the circle of their walls, which had now become too large and were filled with ruins, there gathered, around the bishop resident in each of them, a whole population of clerics and monks, and beside them a lay population employed in their service or support. In the North, one found the same spectacle at the centres of the new dioceses, at Thérouanne, at Utrecht, at Magdeburg, or at Vienna. But here was no trace, properly speaking, of municipal life. A certain number of artisans, some of them serfs, a little weekly market for the most indispensable commodities, sometimes a fair visited by the merchant-adventurers of whom we have spoken above--this is the sum total of economic life. But the situation changes from the moment when the increasing intensity of commerce begins to furnish men with new means of existence. Immediately one discovers an uninterrupted movement of migration of peasants from the country towards the places in which the handling of merchandise, the towing of boats, the service of merchants furnish regular occupations and arouse the hope of gain.