But yet the conviction of the necessity for subduing Britain must have predominated with Roman statesmen. Caesar's conduct would be inconceivable if we do not presuppose that conviction in his case. Augustus at first formally recognised, and never formally disowned, the aim proposed by Caesar, notwithstanding its inconvenience. It was precisely the governments that were the most far-seeing and most tenacious of purpose--those of Claudius, Nero, and Domitian--that laid the foundation for the conquest of Britain, or extended the work; and, after it had taken place, it was never regarded in any such light as, let us say, the conquest by Trajan of Dacia and Mesopotamia. If the maxim of government, elsewhere adhered to almost inviolably, that the Roman empire had simply to fill, but not to extend, its bounds, was permanently set aside only in respect of Britain, the cause lies in the fact that the Celts could not be subdued in such a way as Rome's interest demanded, on the continent alone. This nation was to all appearance more connected than separated by the narrow arm of the sea which parts England and France; the same names of peoples meet us on the one side and on the other; the bounds of the individual states often reach over the Channel; the chief seat of the priestly system, which here more than anywhere else pervaded the whole nationality, was from of old the islands of the North Sea. These islanders indeed were not able to wrest the continent of Gaul from the Roman legions; but, if the conqueror of Gaul himself, and, later, the Roman government in Gaul, pursued other aims than in Syria and Egypt--if the Celts were to be annexed as members to the Italian nation--this task remained quite impracticable, so long as the subjugated and the free Celtic territories touched each other over the sea, and the enemy of the Romans as well as the Roman deserter found an asylum in Britain.[100] In the first instance the subjugation of the southern coast sufficed for this purpose, although the effect was naturally the greater, the farther the free Celtic territory was pushed back.[101] The special regard of Claudius for his Gallic home and his knowledge of Gallic relations may also have played a part in the matter. [Sidenote: Occasion for the war.] [Sidenote: Cunobelinus.]