EARTH SCIENCES IN NINETEENTH CENTURY 677 



Other subjects. In doing so, we are only carrying out our work to its 

 legitimate 'conclusion. It is without question our responsibility to 

 study the ancient inorganic conditions that determined the location 

 and the migration, the development and the extinction of ancient 

 faunas, for these conditions were at least in part geological factors 

 of one kind or another; it is equally our responsibility to study the 

 modern conditions that determine the location of cities and the routes 

 of trade, for these conditions are largely geographical factors; but 

 the examples of organic response here adduced are merely a few of 

 many, and all the rest stand on an equal footing with them, whether 

 they are commonly classed with biology or history, with economics 

 or religion. We long ago saw that the more simple, immediate, and 

 manifest examples of organic, especially of human, responses belonged 

 in the realm of geography; and from this beginning we now reahze 

 that there is no stopping-place till we include all other examples, 

 complex, indirect, or obscure as some of them may be ; for there is a 

 graded series of connecting examples from the most artful human 

 response down to the most unconscious plant response, and from 

 the immediate responses of today back to the earliest responses of 

 the geological ages. 



It would be most arbitrary to draw a division in our studies, when 

 no division exists in the things studied. It is therefore a piece of 

 good fortune that geographers are coming to follow the practice of 

 geologists, and thus to accept among their responsibilities the great 

 breadth of physiographic and ontographic relationships existing 

 today, as geologists have accepted them for the past. And it is also 

 as good fortune that biologists are coming to accept the responsibility 

 of studying environment as well as response ; for only in this way have 

 the earth and its inhabitants really learned to know each other. I 

 rejoice therefore whenever a student of earth science completes his 

 studies by carrying them forward to their organic consequences, as 

 seen from the side of the earth; and again, whenever a student of 

 biology, of language, of economics, of religion, carries his studies back- 

 ward to a consideration of inorganic causes, as seen from the side of 

 life; for thus and thus only we may hope that the knowledge of both 

 causes and consequences shall increase in fulness. Our present 

 understanding of this interdependence, not only of different branches 



