But little is yet known of the vast mass of documents bearing upon nineteenth-century history which are to be found in the archives of Europe; and historians have been tempted to take refuge in the thought that, after all, these papers contain little that is really of great value. How far that is true for any period of the nineteenth century may, I think, be doubted; but for the period during which Castlereagh held office, it can, surely, be urged that the unpublished documents in the Record Office are of real importance. Singularly, little attention has been paid by English historians to this period of history, and but little use has as yet been made of unpublished material. It is true that the collections of papers in the Londonderry correspondence and the Wellington Supplementary Dispatches contain a vast amount of information; but, valuable as this is, it is only a small fragment of the whole, and much of it can only be interpreted by the aid of other evidence. What has already been done in this way has thrown much new light on the character and achievements of Castlereagh. Fyffe was able to appreciate his career and his connexion with the congress system with much more justice, because he had seen some of the documents of the years 1814–15; and Mr. Alison Phillipps' monographs in the ‘Cambridge Modern History’ have already destroyed many of the fictions which had masqueraded as facts during the century. But as yet no detailed study of this period, based upon the archives, has appeared. Castlereagh's career has attracted but little attention and sympathy. There is no detailed account in English of the congress of Vienna, still less of the later congresses of Aix-la-Chapelle, Troppau, and Laibach. Yet, even if it be not admitted that Castlereagh was himself a great statesman, the circumstances of his life make the policy of England during his period of office well worthy of particular attention. From 1814 to 1822 England was connected with the Continent by ties far stronger than any which have bound her before or since. Not merely was she bound by treaties of exceptional character, but her leading statesman had exceptional personal relations with those of the other powers during a period which has never been surpassed in the invention of new methods of diplomacy, and the solution of difficult problems of immense importance. In these questions Castlereagh took a leading, at times a dominant, part. He was the creator of the great treaty which made it certain that Napoleon would no longer rule over France; he was the decisive factor at the Congress of Vienna, for it was he alone who made England take so commanding a position in the critical questions of Poland and Saxony; and he had perhaps a greater share than any other statesman in securing that period of comparative peace for Europe which was the first necessity of its future progress.