252 DAVIS — SYSTEMATIC GEOGRAPHY. [Aprils, 



imaginable types would find their appropriate place in a systematic 

 arrangement. Each of these types might be considered to be the 

 label on a pigeon-hole ; and actual examples would be placed in 

 their appropriate pigeon-hole as fast as they were collected. The 

 compartments designed for common examples would soon be filled ; 

 while others might long remain empty. Such a plan as this greatly 

 promotes systematic observation, for the very fact that a certain 

 pigeon-hole contains no actual form corresponding to its idealized 

 type urges the observer to search for the missing example in dis- 

 tricts where its occurrence is most probable. Revision of an 

 idealized type would naturally be made whenever an example re- 

 sembling it was found ; for however deductive the method of de- 

 veloping types may seem when here stated in the abstract, the 

 actual progress of this sort of study involves repeated oscillations 

 between induction and deduction, in which each process aids the 

 other. The types are therefore not to be thought of as fancy 

 pictures, unreasonably constructed by an ungoverned imagination 

 and arbitrarily fixed by obstinate deduction. They should be the 

 very best imitations of nature that the well-trained mind can con- 

 struct, and they should be held subject to constant revision and 

 correction as fast as observation is extended. 



The conservative geographer will hesitate to construct a frame- 

 work in which his types shall be more numerous than his examples. 

 Indeed it sounds at first rather presumptuous to say that the variety 

 of idealized types can exceed the variety of nature ; but there is no 

 doubt that it can. The earth is after all not so very large ; and 

 when all the examples of physiographic items that it contains shall 

 have been studied out and systematically arranged, it will be easy 

 enough to construct imaginary types that belong between two 

 actual examples. Even if all the items that have existed in all 

 the paleogeographies of the earth's history were brought into 

 systematic arrangement, it may be doubted whether they would fill 

 all the pigeon-holes of a well-imagined framework, so easily can the 

 imagination conceive of a type intermediate with respect to any 

 two neighboring examples. 



It is therefore plainly a profitable exercise for the systematic 

 geographer to elaborate his systematic framework as far as possible ; 

 to increase the number of its little compartments, each bearing an 

 appropriate label ; to arrange all the compartments in as systematic 

 an order as he can develop ; and to devise every means — verbal. 



