t of all, whether the
author can have had exact information, otherwise his statement is
valueless. We next put to ourselves the general question: Was the author
in the habit of altering his sources, and in what manner? And in regard
to each separate second-hand statement we ask whether it has the
appearance of being an exact reproduction or an arrangement. We judge by
the form: when we meet with a passage whose style is out of harmony with
the main body of the composition, we have before us a fragment of an
earlier document; the more servile the reproduction the more valuable is
the passage, for it can contain no exact information beyond what was
already in the source.

VII. In spite of all these investigations, criticism never succeeds in
determining the parentage of all the statements to the extent of finding
out who it was that observed, or even recorded, each fact. In most cases
the inquiry ends in leaving the statement anonymous.

We are thus confronted with a fact, observed we know not by whom nor
how, recorded we know not when nor how. No other science accepts facts
which come in such a condition, without possibility of verification,
subject to incalculable chances of error. But history can turn them to
account, because it does not, like the other sciences, need a supply of
facts which are difficult to ascertain.

The notion of a _fact_, when we come to examine it precisely, reduces to
an affirmative judgment having reference to external reality. The
operations by which we arrive at such a judgment are more or less
difficult, and the risk of error is greater or smaller according to the
nature of the realities investigated and the degree of precision with
which we wish to formulate them. Chemistry and biology need to discern
facts of a delicate order, rapid movements, transient states, and to
measure them in exact figures. History can work with facts of a much
coarser kind, spread over a large extent of space or time, such as the
existence of a custom, of a man, of a group, even of a people; and these
facts may be roughly expressed in vague words conveying no idea of
accurate measurement. With such easily observed facts as these to deal
with, history can afford to be much less exacting with regard to the
conditions of observation. The imperfection of the means of information
is compensated by a natural faculty of being satisfied with information
which can easily be obtained.

Documents supply little else besid