Great Britain is fortunate in this respect also. Its geological formation presents on a small scale all the principal strata from the oldest to the most recent, a fact which secures great diversity within a compact area, an area too compact to allow of divergences of population being produced by differences of geological formation; so that it enjoys the advantages of diversity without its drawbacks. Although a certain degree of differentiation between north and south may be noted, it is not sharp or great enough to be dangerous. But let us imagine that coal and iron had been confined to Scotland. Would there be now the same harmony between the two countries as actually obtains? The United States of America afford a good illustration of this principle, as I have already pointed out; the sub-tropical climate of the southern states gave rise to a differentiation of occupation, and consequently of ideas and interests and sentiments, which was almost fatal to the unity of the nation. A similar differentiation between the agricultural west and the industrial and commercial east seems to be the greatest danger to the future unity of the nation; and the same may be said of the Canadian people. Ireland illustrates well the effects of both kinds of physical influence. The Irish Channel has perpetuated that difference of race and consequent difference of religion, which, but for it, would probably have been wiped out by free intermarriage; while the lack of coal and iron in the greater part of the country has prevented the spread of industrialism, and has thus accentuated the difference between the Irish people and the English. And it is obvious that among the Protestants of Ulster the accessibility of coal and iron, maintaining a divergence of occupations and of interests which prevents racial and cultural blending, perpetuates the racial and traditional differences between them and the rest of the population. CHAPTER VIII FREEDOM OF COMMUNICATION AS A CONDITION OF NATIONAL LIFE Let us consider now very briefly in relation to the life of a nation a second essential condition of all collective mental life—namely, that the individuals shall be in free communication with one another. This is obviously necessary to the formation of national mind and character. It is only through an immense development of the means of communication, especially the printing press, the railway and the telegraph, that the modern Nation-State has become possible, and has become the dominant type of political organism. So familiar are we with this type, that we are apt to identify the Nation and the State and to regard the large Nation-State as the normal type of State and of Nation, forgetting that its evolution was not possible before the modern period.