206 LAY SERMONS, ESSAYS, AND REVIEWS. [xi. 



the influence of a dominant pursuit if I say that I trace a close 

 analogy between these two histories. 



If I study a living being, under what heads does the know 

 ledge I obtain fall ? I can learn its structure, or what we call its 

 ANATOMY ; and its DEVELOPMENT, or the series of changes 

 which it passes through to acquire its complete structure. Then 

 I find that the living being has certain powers resulting from its 

 own activities, and the interaction of these with the activities of 

 other things the knowledge of which is PHYSIOLOGY. Beyond 

 this the living being has a position in space and time, which is 

 its DISTRIBUTION. All these form the body of ascertainable 

 facts which constitute the status quo of the living creature. But 

 these facts have their causes; and the ascertainment of these 

 causes is the doctrine of AETIOLOGY. 



If we consider what is knowable about the earth, we shall 

 find that such earth-knowledge if I may so translate the word 

 geology falls into the same categories. 



What is termed stratigraphical geology is neither more nor 

 less than the anatomy of the earth ; and the history of the 

 succession of the formations is the history of a succession of such 

 anatomies, or corresponds with development, as distinct from 

 generation. 



The internal heat of the earth, the elevation and depression of 

 its crust, its belchings forth of vapours, ashes, and lava, are its 

 activities, in as strict a sense as are warmth and the movements 

 and products of respiration the activities of an animal. The 

 phenomena of the seasons, of the trade winds, of the Gulf-stream, 

 are as much the 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 organization 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 physiology, 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 



