d of direct observation; but historians have no
choice: it is the _only_ method of arriving at past facts, and we shall
see later on[58] how, in spite of these disadvantages, it is possible
for this method to lead to scientific knowledge.

The detailed analysis of the reasonings which lead from the inspection
of documents to the knowledge of facts is one of the chief parts of
Historical Methodology. It is the domain of criticism. The seven
following chapters will be devoted to it. We shall endeavour, first of
all, to give a very summary sketch of the general lines and main
divisions of the subject.

I. We may distinguish two species of documents. Sometimes the past event
has left a material trace (a monument, a fabricated article). Sometimes,
and more commonly, the trace is of the psychological order--a written
description or narrative. The first case is much simpler than the
second. For there is a fixed relation between certain physical
appearances and the causes which produced them; and this relation,
governed by physical laws, is known to us.[59] But a psychological
trace, on the other hand, is purely symbolic: it is not the fact itself;
it is not even the immediate impression made by the fact upon the
witness's mind, but only a conventional symbol of that impression.
Written documents, then, are not, as material documents are, valuable
by themselves; they are only valuable as signs of psychological
operations, which are often complicated and hard to unravel. The immense
majority of the documents which furnish the historian with
starting-points for his reasonings are nothing else than traces of
psychological operations.

This granted, in order to conclude from a written document to the fact
which was its remote cause--that is, in order to ascertain the relation
which connects the document with the fact--it is necessary to reproduce
the whole series of intermediate causes which have given rise to the
document. It is necessary to revive in imagination the whole of that
series of acts performed by the author of the document which begins with
the fact observed by him and ends with the manuscript (or printed
volume), in order to arrive at the original event. Such is the aim and
such the process of critical analysis.[60]

First of all we observe the document. Is it now in the same state as
when it was produced? Has it deteriorated since? We endeavour to find
out how it was made in order to restore it, if need be, to it