108 W. M. DAVIS RELATION OF GEOGRAPHY TO GEOLOGY 



product of the imagination and not directly of observation, they can be 

 rightly conceived only by use of a trained scientific imagination, for they 

 are careful deductions from successful theories, the theories being based 

 on abundant observation and induction, and the deductions being tested 

 by repeated confrontation with facts. For this reason explanatory con- 

 cepts represent the sum of pertinent knowledge thus far gathered, while 

 empirical concepts represent only the beginning of the sum, for explana- 

 tory concepts contain all that is valuable in empirical concepts and a great 

 deal more besides. Inborn temperament and habit of thought as deter- 

 mined by education may truly have much to do in determining which 

 kind of equipment a geographer will use; but these vestiges of the past 

 are not always our best guides when we have to make judgments regard- 

 ing the future. 



TREND OF MODERN GEOGRAPHY TOWARDS EXPLANATORY TREATMEN7 



The direction of modern progress in all branches of geography is dis- 

 tinctly toward the fuller development and the more general use of a men- 

 tal equipment consisting of explanatory concepts. Xo one who compares 

 geographical writings of fifty years ago and of the last ten or twenty years 

 can fail to recognize this manifest tendency. If time permitted, an inter- 

 esting stor}^ could be here introduced regarding the gradual progress from 

 the old-fashioned empirical description of such features as shorelines 

 toward their more thorough-going, more comprehensive, more advanced"* 

 and mature, modern and explanatory treatment, or from the old-fash- 

 ioned, blindly empirical description of our prairies to their newer-fash- 

 ioned, illuminating, explanatory description, or from the meaningless, 

 barren, empirical description of mountains in the older texts to theii* 

 highly significant, fruitful, explanatory descrij)tion in more modern 

 books. N'o one who is aware of the change thus made and of the great 

 progress that it marks is willing to return from the newer-fashioned to 

 the older-fashioned method of treating land forms.' Geography is today 

 no longer the backward child that it was a century ago ; it is grooving up, 

 even if it has not yet shown many signs of so rapid, indeed of so pre- 

 cocious a development as that of its younger sister, geology. The chief 

 cause of the modern progress of geography is not the discovery of more 

 mountains, more capes, more rivers, more islands ; it is not the more 

 elaborate enumeration of the kinds of plants and animals that inhabit a 

 region, nor the fuller account of the location of cities and the boundaries 

 of states, but the adoption, in the treatment of all geographical facts, of 

 the evolutionary philosophy that has so profoundly modified all natural 

 sciences ; in a word, the adoption of explanatory theoretical concepts and 

 terms for the description of observed facts. 



