The fact that settlement originally followed the course of rivers is abundantly shown by the number of cities, towns, monasteries, abbeys and conventual establishments set up of old in the Thames valley. The convenience, also, of water transport must have had much to do with the locating of a University at Oxford, on the Thames, just as it did with the establishment of a University at Cambridge, on the Cam, each being thus rendered accessible to scholars from Scotland and elsewhere who would have found it impracticable to make so long a journey under the early conditions of road travel. The Thames became, further, the main highway for the various counties through which it flowed, included therein being some of the most fertile districts in the land; and, though London may owe its pre-eminence mainly to foreign trade, passing between the port of London and the sea, the facilities for communication offered above the port of London by the Thames for the full extent of its navigable length were, in the pre-railway days more especially, of incalculable advantage both to the districts served thereby and to the Metropolis itself. This advantage becomes still more striking when we take into account the rivers that form important tributaries of the Thames. The Lea was described in a statute of 1424 as "one of the great rivers, which extendeth from the town of Ware till the water of the Thames, in the counties of Hertford, Essex and {126}Middlesex"; and along this river there was carried at one time a very considerable quantity of produce and merchandise. The history of Ware goes back to, at least, the ninth century, when the Danes took their ships up to the town but were outmanoeuvred by King Alfred, who diverted the stream, and left the vessels stranded. Not only was the founding of Ware on the spot where it stands due to the convenience of water communication, but Ware itself was one of the ideal ports of the time, inasmuch as it was so far inland, and was in convenient reach of several counties.