And as a second illustration of the way in which changing conditions are altering political questions, let the reader take his atlas and consider the case of that impregnable fastness, that great naval station, that Key to the Mediterranean, Gibraltar.  British boys are brought up on Gibraltar and the Gibraltar idea.  To the British imagination Gibraltar is almost as sacred a national symbol as the lions in Trafalgar Square.  Now, in his atlas the reader will almost certainly find an inset map of this valuable possession, coloured bright red.  The inset map will have attached to it a small scale of miles.  From that he will be able to satisfy himself that there is not an inch of the rock anywhere that is not within five miles or less of Spanish land, and that there is rather more than a semicircle of hills round the rock within a range of seven or eight miles.  That is much less than the range of a sixteen-inch gun.  In other words, the Spaniards are in a position to knock Gibraltar to bits whenever they want to do so, or to smash and sink any ships in its harbour.  They can hit it on every side.  Consider, moreover, that there are long sweeps of coast north, south, and west of the Rock, from which torpedoes could be discharged at any ship that approached.  Inquire further where on the Rock an aeroplane can land.  And having ascertained these things, ask yourself what is the present value of Gibraltar?

I will not multiply disagreeable instances of this sort, though it would be easy enough to do so in the case both of France and Italy as well as of Great Britain.  I give them as illustrations of the way in which everywhere old securities and old arrangements must be upset by the greater range of modern things.  Let us get on to more general conditions.  There is not a capital city in Europe that twenty years from now will not be liable to a bombing raid done by hundreds or even thousands of big aeroplanes, upon or even before a declaration of war, and there is not a line of sea communication that will not be as promptly interrupted by the hostile submarine.  I point these things out here only to carry home the fact that the ideas of sovereign isolation and detachment that were perfectly valid in 1900, the self-sufficient empire, Imperial Zollverein and all that stuff, and damn the foreigner! are now, because of the enormous changes in range of action and facility of locomotion that have been going on, almost as wild—­or would be if we were not so fatally accustomed to them—­and quite as dangerous, as the idea of setting up a free and sovereign state in the Isle of Dogs.  All the European empires are becoming vulnerable at every point.  Surely the moral is obvious.  The only wise course before the allied European powers now is to put their national conceit in their pockets and to combine to lock up their foreign policy, their trade interests, and all their imperial and international interests into a League so big as to be able to withstand the most sudden and treacherous of blows.  And surely the only completely safe course for them and mankind—­hard and nearly impossible though it may seem at the present juncture—­is for them to lock up into one unity with a democratized Germany and with all the other states of the earth into one peace-maintaining League.