After all, there is no lack of guides in the present age. The number of memoir-writers and newspaper correspondents is legion; and I have come to believe that they are fully as trustworthy as similar witnesses have been in any age. The very keenness of their rivalry is some guarantee for truth. Doubtless competition for good "copy" occasionally leads to artful embroidering on humdrum actuality; but, after spending much time in scanning similar embroidery in the literature of the Napoleonic Era, I unhesitatingly place the work of Archibald Forbes, and that of several knights of the pen still living, far above the delusive tinsel of Marbot, Thiébault, and Ségur. I will go further and say that, if we could find out what were the sources used by Thucydides, we should notice qualms of misgiving shoot through the circles of scientific historians as they contemplated his majestic work. In any case, I may appeal to the example of the great Athenian in support of the thesis that to undertake to write contemporary history is no vain thing. Above and beyond the accounts of memoir-writers and newspaper correspondents there are Blue Books. I am well aware that they do not always contain the whole truth. Sometimes the most important items are of necessity omitted. But the information which they contain is enormous; and, seeing that the rules of the public service keep the original records in Great Britain closed for well-nigh a century, only the most fastidious can object to the use of the wealth of materials given to the world in _Parliamentary Papers_. Besides these published sources there is the fund of information possessed by public men and the "well-informed" of various grades. Unfortunately this is rarely accessible, or only under conventional restrictions. Here and there I have been able to make use of it without any breach of trust; and to those who have enlightened my darkness I am very grateful. The illumination, I know, is only partial; but I hope that its effect, in respect to the twilight of diplomacy, may be compared to that of the Aurora Borealis lights. After working at my subject for some time, I found it desirable to limit it to events which had a distinctly formative influence on the development of European States. On questions of motive and policy I have generally refrained from expressing a decided verdict, seeing that these are always the most difficult to probe; and facile dogmatism on them is better fitted to omniscient leaderettes than to the pages of an historical work. At the same time, I have not hesitated to pronounce a judgment on these questions, and to differ from other writers, where the evidence has seemed to me decisive. To quote one instance, I reject the verdict of most authorities on the question of Bismarck's treatment of the Ems telegram, and of its effect in the negotiations with France in July 1870.