The core study of geography is the study of places, that is the analysis of the significant differences that distinguish the various areas of the world from each other. Among the differences that are significant to this areal differentiation, one of the more obvious are differences in landforms; one of the least obvious to the eye, but nonetheless important in molding the character of areas, are the differences in their political organization. In pursuing these and other separate topics, geographers "radiate out in diverse directions" "and for various distances, toward the cores of other disciplines." As long as they realise where they are in reference to the central core, they may hope to understand each other purposes.

R. Hartshorne (1950) "The functional approach in political geography," Annals of the Association of American Geographers Vol. 40 (2), p. 95