Now let me make myself as clear as I can be about the central idea upon which the whole of the arguments in this lecture rests. It is this: forgive me for a repetition--that there has been a complete alteration in the range and power of human activities in the last hundred years. Men can react upon men with a rapidity and at a distance inconceivable a hundred years ago. This is particularly the case with locomotion and methods of communication generally. I will not remind you in any detail of facts with which you are familiar; how that in the time of Napoleon the most rapid travel possible of the great conqueror himself did not average all over as much as four and a half miles an hour. A hundred and seven miles a day for thirteen days--the pace of his rush from Vilna to Paris after the Moscow disaster--was regarded as a triumph of speed. In those days, too, it was a marvel that by means of semaphores it was possible to transmit a short message from London to Portsmouth in the course of an hour or so. Since then we have seen a development of telegraphy that has at last made news almost simultaneous about the world, and a steady increase in the rate of travel until, as we worked it out in the Civil Air Transport Committee in London, it is possible, if not at present practicable, to fly from London to Australia, half way round the earth, in about eight days. I say possible, but not practicable, because at present properly surveyed routes, landing grounds and adequate supplies of petrol and spare parts do not exist. Given those things, that journey could be done now in the time I have stated. This tremendous change in the range of human activities involves changes in the conditions of our political life that we are only beginning to work out to their proper consequences to-day. It is a curious thing that America, which owes most to this acceleration in locomotion, has felt it least. The United States have taken the railway, the river steamboat, the telegraph and so forth as though they were a natural part of their growth. They were not. These things happened to come along just in time to save American unity. The United States of to-day were made first by the river steamboat, and then by the railway. Without these things, the present United States, this vast continental nation, would have been altogether impossible. The westward flow of population would have been far more sluggish. It might never have crossed the great central plains. It took, you will remember, nearly two hundred years for effective settlement to reach from the coast to the Missouri, much less than half-way across the continent. The first state established beyond the river was the steamboat state of Missouri in 1821. But the rest of the distance to the Pacific was done in a few decades.