institutions), are not
isolated in reality, that they have common characteristics, and that
they are closely enough connected for a change in one of them to bring
about a change in another. This is a fundamental idea of the _Esprit des
Lois_ of Montesquieu. This bond of connection, sometimes called
_consensus_, has received the name of _Zusammenhang_ from the German
school. From this conception has arisen the theory of the _Volksgeist_
(the mind of a people), a counterfeit of which has within the last few
years been introduced into France under the name of "ame nationale."
This conception is also at the bottom of the theory regarding the soul
of society which Lamprecht has expounded.

After the rejection of these mystical conceptions there remains a vague
but incontrovertible fact, the "solidarity" which exists between the
different habits of one and the same people. In order to study it with
precision it would be necessary to analyse it, and a connecting bond
cannot be analysed. It is thus quite natural that this part of social
science should have remained a refuge for mystery and obscurity.

By the comparison of different societies which resemble or differ from
each other in a given department (religion or government), with the
object of discovering in what other departments they resemble or differ
from each other, it is possible that interesting empirical results might
be obtained. But, in order to _explain_ the _consensus_, it is necessary
to work back to the facts which have produced it, the common causes of
the various habits. We are thus obliged to undertake the investigation
of causes, and we enter the province of what is called _philosophical_
history, because it investigates what was formerly called the
_philosophy_ of facts--that is to say, their permanent relations.

IX. The necessity of rising above the simple determination of facts in
order to _explain_ them by their _causes_, a necessity which has
governed the development of all the sciences, has at length been felt
even in the study of history. Hence have arisen systematic philosophies
of history, and attempts to discover historical laws and causes. We
cannot here enter into a critical examination of these attempts, which
the nineteenth century has produced in so great number; we shall merely
indicate what are the ways in which the problem has been attacked, and
what obstacles have prevented a scientific solution from being reached.

The most natur