318 GEOLOGICAL REFORM * 



results of the reaction between these inner 

 activities and outward forces, as are the budding 

 of the leaves in spring and their falling in autumn 

 the effects of the interaction between the organ- 

 isation of a plant and the solar light and heat. 

 And, as the study of the activities of the living being 

 is called its physiology, so are these phenomena 

 the subject-matter of an analogous telluric physio- 

 logy, to which we sometimes give the name of 

 meteorology, sometimes that of physical geography, 

 sometimes that of geology. Again, the earth has 

 a place in space and in time, and relations to 

 other bodies in both these respects, which con- 

 stitute its distribution. This subject is usually 

 left to the astronomer; but a knowledge of its 

 broad outlines seems to me to be an essential 

 constituent of the stock of geological ideas. 



All that can be ascertained concerning the 

 structure, succession of conditions, actions, and posi- 

 tion in space of the earth, is the matter of fact of its 

 natural history. But, as in biology, there remains 

 the matter of reasoning from these facts to their 

 causes, which is just as much science as the other, 

 and indeed more ; and this constitutes geological 

 aetiology. 



Having regard to this general scheme of geo- 

 logical knowledge and thought, it is obvious that 

 geological speculation may be, so to speak, ana- 

 tomical and developmental speculation, so far as it 

 relates to points of stratigraphical arrangement 



