He is to keep before his eyes the fact that chance is merely a
synonym for our ignorance; that the reign of law pervades the
domain of history as much as it does that of political science. He
is to accustom himself to look on all occasions for rational and
natural causes. And while he is to recognise the practical utility
of the supernatural, in an educational point of view, he is not
himself to indulge in such intellectual beating of the air as to
admit the possibility of the violation of inviolable laws, or to
argue in a sphere wherein argument is A PRIORI annihilated. He is
to be free from all bias towards friend and country; he is to be
courteous and gentle in criticism; he is not to regard history as a
mere opportunity for splendid and tragic writing; nor is he to
falsify truth for the sake of a paradox or an epigram.

While acknowledging the importance of particular facts as samples
of higher truths, he is to take a broad and general view of
humanity. He is to deal with the whole race and with the world,
not with particular tribes or separate countries. He is to bear in
mind that the world is really an organism wherein no one part can
be moved without the others being affected also. He is to
distinguish between cause and occasion, between the influence of
general laws and particular fancies, and he is to remember that the
greatest lessons of the world are contained in history and that it
is the historian's duty to manifest them so as to save nations from
following those unwise policies which always lead to dishonour and
ruin, and to teach individuals to apprehend by the intellectual
culture of history those truths which else they would have to learn
in the bitter school of experience,