786 THE AMERICAN JOURNAL OF SOCIOLOGY
it all that it sets out to show about its own routes and connections. From that map alone, however, we should be likely to get little or no conception of the topography and climate, of the kinds of soil or varieties of products, of the density of population, of the political divisions, or even of the precise geographical relations of the country through which the road runs. In order to have the knowledge necessary for all departments of life in the locality, it is necessary for us to possess the information that would be represented by a series of geological, topographical, meteorological, political, and even transportation charts, picturing in turn different phases of natural and artificial conditions within the selfsame portion of territory covered by the map of a single railroad system.
In a somewhat analogous way political economy deals with the system of industrial lines of communication in a society — the industrial nerves and arteries of the body politic, so to speak. But the life of society, or the social fact or social process, is a vast system of physical, physiological, psychological, and personal action and reaction. The associational process is this social reality when we consider it in motion. In order to understand it we have to comprehend not merely the industrial element. That would be like seeing only one thread or figure that runs through the design of a tapestry. To know the social fact and the social process we have to be able to take in all these departments of action that make up the fact and the process ; i. e., the complete design of the fabric. We have to understand what these differ- ent kinds of action have to do with each other, and how each reacts upon the others.
When we speak of all this in cold blood, it seems to be a far-off and vague affair, with which we have the least possible concern. That, however, is the same mistake which we make if we think we have no concern with what the chemist calls "sodium chloride." When we find out that it is merely the salt that we want to use every day, we discover that it is our concern. In the same way we may be indifferent to the subject of "hydrous oxide," but if it is presented to us as drinking water we may see the wisdom of knowing something about it.
