82 Thomas Henry Huxley 



discount any quantity of hypothetical paper. It has kept be- 

 fore our ej^es the power of the infinitely little, time being 

 granted, and has compelled us to exhaust known causes before 

 flying to the unknown." 



But there was a third influence at work in geology, an 

 inflnence which ma}' best be described in Huxley's 

 own words : 



"I shall not make what I have to say on this head clear 

 unless I diverge, or seem to diverge, for a while, from the 

 direct path of my discourse so far as to explain what I take to 

 be the scope of geology itself. I conceive geology to be the 

 history of the earth, in precisely the same sense as biology is 

 the history of living beings ; and I trust you will not think 

 that I am overpowered by 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 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 coustitute the status quo of the living creature. But 

 these facts have their causes ; and the ascertainment of these 

 causes is the doctrine of Etiology. 



"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 suc- 

 cession of the formations is a history of the 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 belching forth of vapours, ashes, and lava, are 



