urse of development and
formation. They arise from the necessity of finding a point of departure
in the confused spectacle which human events present to him who wishes
to narrate them; and they serve thenceforth, so to speak, as a title,
category or index to that inevitable division of labor, by the extension
of which the historico-social material has, up to this time, been
theoretically elaborated. In this domain of knowledge, as well as in
that of the natural sciences, the unity of real principle and the unity
of formal treatment are never found at the first start, but only after a
long and troublous road. So that again from this point of view the
analogy affirmed by Engels between the discovery of historical
materialism and that of the conservation of energy appears to us
excellent.

The provisional orientation, according to the convenient system of what
are called factors, may, under given circumstances, be useful also to us
who profess an altogether unitary principle of historic interpretation,
if we do not wish simply to rest in the domain of theory, but wish to
illustrate, through personal research, a definite period of history. As
in that case we must proceed to direct and detailed research, we must
first of all follow the groups of facts that seem pre-eminent,
independent, or detached in the aspects of immediate experience. We
should not imagine, in fact, that the unitary principle so well
established, at which we have arrived in the general conception of
history, may, like a talisman, act always and at first sight, as an
infallible method of resolving into simple elements the immense area and
the complicated gearing of society. The underlying economic structure,
which determines all the rest, is not a simple mechanism whence emerge,
as immediate, automatic and mechanical effects, institutions, laws,
customs, thoughts, sentiments, ideologies. From this substructure to all
the rest, the process of derivation and of mediation is very
complicated, often subtile, tortuous and not always legible.

The social organization is, as we already know, constantly unstable,
although that does not seem evident to every one, except at the time
when the instability enters upon that acute period which is called a
revolution. This instability, with the constant struggles in the bosom
of that same organized society, excludes the possibility for men coming
to an agreement which might involve a new start at living an animal
life.