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.

For the most part, however, I have dealt only with external events,
pointing out now and again the part which they have played in the great
drama of human action still going on around us. This limitation of aim
has enabled me to take only specific topics, and to treat them far more
fully than is done in the brief chronicle of facts presented by MM.