632 THE AMERICAN JOURNAL OF SOCIOLOGY
tend, after sufficient time, to cause the assimilation of a large percentage of those within their range, so that among people who are in free communication with each other prominent forms and effects of social activity become prevalent, and are spoken of as " national traits ; " though the phrase properly means only that these are rather more prevalent among a given population than elsewhere, and not by any means that they are peculiar to the nation described, nor universal among its people. Not one of these so-called national traits is likely to be universal among the population, and it may be that no single individual exhibits them all. Moreover, the phrase should not be understood to mean that the social radiation to which the prevalence of such traits is due is hemmed in by national boundaries, nor necessarily that it originated within them. The study of great groups, like the nation, helps, moreover, to a comprehension of the interaction of different social processes. The study of smaller societies may not so illuminate the fact that the activity which they have in common is affected and determined by many other activities which they do not have in common. A study of political activity may sooner lead to the perception that particular group activities are deter- mined by many other activities. For it is clear that political activities are affected by activities of many other kinds. The interdependence of different forms of social activity has been observed by the keenest students of each politico-national science. And illustration of such interdependence was the essential service of the biological analogy. But it is erroneous to jump to the conclusion that because political activities are truly national, therefore all the other activities that affect or are affected by the political are parts of a national unity. Political activities them- selves constitute a true unity which is affected by other activities, which are international, sectional, personal, and in every possible way uncoextensive with the nation or state and in contrast with its unity. It may be possible to think of any unity as including all that is related to it. But where will you draw a line around such a unity? It may be possible to think of the unity of a national society as built up out of the heterogeneous activities 6f portions of the population activities which they do not share
