THE DEFINITION OF THE CITY 547
being distributed over the whole of the city. A city of the former kind might be called a segmental or partitioned city, and that of the latter an undivided or homogeneous city, these terms applying to the urban territory, not to the urban community which is always complex, divided, heterogeneous.
Thus the city is in itself a matter of differentiation. Just as it is a complex community, so has it necessarily a heterogeneous and differentiated structure. Although its organisation is natu- rally and essentially a phenomenon of social differentiation, the same is not necessarily true of its functioning (fonctionment) . The latter presents two aspects.
I. Considered in its ensemble and as a whole, the city has an industrial function, i. e., it is the seat of a group of activities for transforming economic goods. This function may or may not be differentiated. The city may be the seat of a complex of activities or "industries," including the industry of agriculture. It may on the contrary develop within itself more or less exclusively certain industrial functions. The loss of the agricultural function to the city, which becomes the special seat of "industry," is an early differentiation of this sort. For there arises, as Adam Smith and, later, Stuart Mill have pointed out, a division of labor between the city and the country. At a more advanced stage the city specializes in certain kinds of industrial activities, and thence arises a division of labor between the cities, of which Sombart has classified the types and measured the influence upon the in- ternal arrangement of the industries in the city itself.
II. From this we are led to consider the functioning of the city under its second or internal aspect. If we recall the well- known propositions and classifications, all of which treat the city from the external point of view, it will be seen that our inquiry tends to give more importance to the other, the internal, point of view, to define the city as an industrial phenomenon and to classify its types less by its external functional characteristics than by its internal functional characteristics. Thus we take up a position quite different from that which the economists are accustomed to occupy, as appears from what follows.
The city, according to the definition which we have g^ven, is
