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 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