from written tradition, or from oral tradition? Do
we possess several traditions of different bias, or a single tradition?
Do we possess documents of different classes or of one single class? Is
our information vague or precise, detailed or summary, literary or
positive, official or confidential?

The natural tendency is to forget, in construction, the results yielded
by criticism, to forget the incompleteness of our knowledge and the
elements of doubt in it. An eager desire to increase to the greatest
possible extent the amount of our information and the number of our
conclusions impels us to seek emancipation from all negative
restrictions. We thus run a great risk of using fragmentary and
suspicious sources of information for the purpose of forming general
impressions, just as if we were in possession of a complete record. It
is easy to forget the existence of those facts which the documents do
not describe (economic facts, slaves in antiquity), it is easy to
exaggerate the space occupied by facts which are known to us (Greek art,
Roman inscriptions, mediaeval monasteries). We instinctively estimate the
importance of facts by the number of the documents which mention them.
We forget the peculiar character of the documents, and, when they all
have a common origin, we forget that they have all subjected the facts
to the same distortions, and that their community of origin renders
verification impossible; we submissively reproduce the bias of the
tradition (Roman, orthodox, aristocratic).

In order to resist these natural tendencies, it is enough to pass in
review the whole body of facts and the whole body of tradition, before
attempting to draw any general conclusion.

VII. Descriptive formulae give the particular character of each small
group of facts. In order to obtain a general conclusion, we must combine
these detailed results into a general formula. We must not compare
together isolated details or secondary characteristics,[208] but groups
of facts which resemble each other in a whole set of characteristics.

We thus form an aggregate (of institutions, of groups of men, of
events). Following the method indicated above, we determine its
distinguishing characteristics, its extent, its duration, its quantity
or importance.

As we form groups of greater and greater generality we drop, with each
new degree of generality, those characteristics which vary, and retain
those which are common to all the members of t