s_ that evolve, in the strict sense of the word.[196] When a
change takes place in a usage, this means that the men who practise it
have changed. Now, men are not built in water-tight compartments
(religious, juridical, economic) within which phenomena can occur in
isolation; an event which modifies the condition of a man changes his
habits in a great variety of respects. The invasion of the Barbarians
influenced alike language, private life, and political institutions. We
cannot, therefore, understand evolution by confining ourselves to a
special branch of history; the specialist, even for the purpose of
writing the complete history of his own branch, must look beyond the
confines of his own subject into the field of general events. It is the
merit of Taine to have asserted, with reference to English literature,
that literary evolution depends, not on literary events, but on facts of
a general character.

The general history of individual facts was developed before the special
histories. It contains the residue of facts which have not found a place
in the special histories, and has been reduced in extent by the
formation and detachment of special branches. As general facts are
principally of a political nature, and as it is more difficult to
organise these into a special branch, general history has in practice
been confounded with political history (_Staatengeschichte_).[197] Thus
political historians have been led to make themselves the champions of
general history, and to retain in their constructions all the general
facts (migrations of peoples, religious reforms, inventions, and
discoveries) necessary for the understanding of political evolution.

In order to construct general history it is necessary to look for all
the facts which, because they have produced changes, can explain either
the state of a society or one of its evolutions. We must search for them
among all classes of facts, displacements of population, artistic,
scientific, religious, technical innovations, changes in the _personnel_
of government, revolutions, wars, discoveries of countries.

That which is important is that the fact should have had a decisive
influence. We must therefore resist the natural temptation to divide
facts into great and small. It goes against the grain to admit that
great effects may have had small causes, that Cleopatra's nose may have
made a difference to the Roman Empire. This repugnance is of a
metaphysical order; it s