A third great tidal river is also concerned with these seas, also helps to determine their commerce, also supports its great inland town. That river is the Seine, and I shall, in the pages which follow, use the Seine also for the example it affords in the analogies and contrasts and parallels which I propose to draw. But it is the Scheldt and the Thames which still remain the greater opponents. The united political life of Gaul, which was inherited and transformed by the French Monarchy, forbade the growth of a great commerce to the north. Paris became not only the political centre of France but its main market as well, and to-day the water carriage of Paris--that is, the traffic of its port--is greater than that of any maritime town in the country. Only if Normandy had developed as an independent state would Rouen have become what Antwerp and London have become. Rouen would then have been, without doubt, the point of transhipment between the inland and the maritime waterways, and the distance of the town from coal would hardly have affected it more than does the distance of London. Its situation as a political junction would have determined its greatness. As it is the Lower Seine may be set beside the Scheldt and the Thames for an illustration in their topography and in the origins of their human settlements, but it does not afford a true commercial parallel to-day, and Rouen is no third rival to the two great ports which are before our eyes and in this generation struggling for primacy. It is the custom of sailors to speak of that water by which they approach a great town under the name of the town. Men coming up from Yarmouth Roads inland do not speak of the Yare, but of Norwich River. For, to the sailor the river is but a continuation of, or an access to, his port, and the Lower Thames is thus universally known from the sea as London River. The term is an accidental one, but it contains the true history of the connection between the stream and the town. The Thames made London. London is a function of the Thames, and it is in such a connection that I propose to regard it in this essay: London as the great crossing place of the Thames, and as the custodian and fruit of what early may have been the chief ferry, but has for nearly two thousand years been the chief bridge; London as the market of which the Thames is the approach and the port; London as a habitation of which the great street is the Thames, a street for centuries the main highway of its people, lost for a time and now recovering its ancient use; London as the civil and religious head of revenues which were drawn from the Thames Valley; and London as the determinant, through its position upon the Thames, of English military history. [Illustration: ERITH]