our own societies it is necessary to understand rudimentary societies, for our civilization developed out of their barbarism and their savagery; our social organizations have passed through phases which are recalled by those with which these rude societies stopped developing. If we wish to explain our actual modern states, we must study ancient states, and also the inferior contemporary groups which they resemble in so many particulars. It is only by exact knowledge of the past that we can interpret the present and look into the future.
Nor is this all. Sociology is not content to study all societies, but it proposes to study all classes of social facts in all of these societies. Now the mission of economic science is to examine only a single kind of facts. But it would be very useful to the economist to be able to find in another science a resume of the totality of facts contiguous to those which he makes his specialty. This is precisely the service which sociology ought to render. The economic function, which corresponds in society with the function of nutrition in the individual, is without doubt the most rudimentary function, the basis of all others. Nevertheless, if we wish to comprehend its functional action it is necessary to know in addition the structure of the social body in which this function operates—just as to understand the nutrition of an animal it is necessary to know its individual anatomy. Now, as we have seen, sociology occupies itself in the beginning with determining the anatomy of the society studied, with describing its double environment—the external or physical environment (soil, climate, minerals, flora and fauna), and the internal or human environment (race, population, subordinate human groups). But further, after the economic function come the other functions which we have already enumerated—genetic, moral, religious, political, etc. If these are in a sense derived from the first, it is evident also that once differentiated they acquire an existence of their own, and that they react upon the economic phenomena—just as, in the individual, thought, while posterior to nutrition, exercises upon the latter an indisputable influence. It is thus, for example, that the moral ideas of
