used as a basis of study. In order to
study intellectual habits (language, religion, art, science) we shall
not take a political unit, the nation, but the group consisting of those
who shared the habit in question. In order to study economic facts we
shall choose a group united by a common economic interest; we shall
reserve the political group for the study of social and political facts,
and we shall discard _race_[193] altogether.

Even in those points in which a group is homogeneous it is not entirely
so; it is divided into sub-groups, the members of which differ in
secondary habits; a language is divided into dialects, a religion into
sects, a nation into provinces. Conversely, one group resembles other
groups in a way that justifies its being regarded as contiguous with
them; in a general classification we may recognise "families" of
languages, arts, and peoples. We have, then, to ask: How was a given
group sub-divided? Of what larger group did it form a part?

It then becomes possible to study methodically a given habit, or even
the totality of the habits belonging to a given time and place, by
following the table given above. The operation presents no difficulties
of method in the case of those species of facts which appear as
individual and voluntary habits--language, art, sciences, conceptions,
private usages; here it is enough to ascertain in what each habit
consisted. It is merely necessary to distinguish carefully between those
who originated or maintained habits (artists, the learned, philosophers,
introducers of fashions) and the mass who accepted them.

But when we come to social or political habits (what we call
institutions), we meet with new conditions which produce an inevitable
illusion. The members of the same social or political group do not
merely habitually perform _similar_ actions; they influence each other
by _reciprocal_ actions, they command, coerce, pay each other. Habits
here take the form of _relations_ between the different members; when
they are of old standing, formulated in official rules, imposed by a
visible authority, maintained by a special set of persons, they occupy
so important a place in life, that, to the persons under their
influence, they appear as external realities. The men, too, who
specialise in an occupation or a function which becomes the dominating
habit of their lives, appear as grouped in distinct categories (classes,
corporations, churches, governments); and th