It was while I was meditating on these thoughts in mid-ocean that the idea occurred to me of writing something different from a book of impressions on Argentina and Brazil. Too many books of impressions of the two Americas are written in Europe; and literature of this sort, as copious as it is useless, has justly satiated the public. Inasmuch as this idea of progress implies a great conflict of tendencies, from which may arise a profound upheaval of our civilisation, why should I not contrast in a book the two conceptions of progress, that which America has created and is trying to impose on the world, and that which is even now professed in Europe by the classes most faithful to tradition, and which they ought to seek to defend? If I succeeded in giving a vivid representation of this conflict, should I not have described a living part of America better than if I had merely accumulated thousands of detached impressions and observations? And so the idea flashed across my mind of writing a dialogue introducing some Europeans and Americans who on board a steamer in mid-ocean discussed Europe and America, that is to say, progress, in the sense proper to the word as well as in the sense given to it by the Americans. Is not the dialogue an ancient and glorious literary form? It is true that for many reasons it has lately been neglected, one particular reason being, that in modern life, busy and exhausting as it is, it is difficult to find a scene which will give verisimilitude to a conversation lasting several days. Modern civilisation is a civilisation of much action and little discussion. However, there is still one scene left in modern life on which one can stage with artistic verisimilitude a discussion lasting several days: a transatlantic liner. A liner is perhaps the only spot in the modern world where one may find discussion holding the field. Usually discussions on board ship deal with frivolous and empty topics. Why might not a writer suppose, however, that for once in a way, four or five serious-minded persons met on board a liner and began a casual talk which later developed into a discussion of one of the gravest of the problems which oppress our own generation, no less than every one of its predecessors?