In the library, for instance, territorial expansion has frequently claimed the right of way. It has been evident that wide regions within the municipality were not reached by the library’s activities; hence the establishment of branches--practically classification on a regional or territorial basis. Next, perhaps, some other need is pushed forward--say, the necessity for special care given to the children of the community. Here is a non-territorial basis for classification, founded only upon the age of the library’s users. These are not classes and sub-classes, but are entirely different primary systems of classification, whose dividing lines cross and do not run parallel. A man who should sit down and try to evolve, at first hand, some sort of classification of library work, might adopt one or the other, but not both. In one case he might divide his city into districts, with district superintendents and local librarians under each; in the other, he might divide his users by ages and tastes and have a superintendent for each. In neither case would there be cross-classification, with its over-lapping classes and consequent interferences of jurisdiction. But this is not the way that things work out. The librarian finds it necessary to have his geographical subdivisions and also those based on age, and he adopts others also as they appear desirable, without much regard for the logic of classification. If he does take it into account, he feels that the troubles resulting from conflicts of jurisdiction will be more easily dealt with than those consequent upon a refusal to respond to the present demands of the work. Also--and this is an important factor--conflicts of jurisdiction, no matter how inevitable, are in the future, and the present demands of the work look vastly larger and press with insistence. Is there any wonder that he does what lies immediately before him and lets the future take care of itself?