58 SCIENCE OF THE COSMOS. 



the successive phases through which they have previously 

 passed. The mode of formation, or of production, is often 

 an important element of their character. Nor is it in the 

 organic world only that matter is constantly undergoing 

 change, and dissolving to be formed into new combinations : 

 the globe on which we live also reveals the knowledge of 

 an earlier state: the strata of sedimentary rocks, which 

 compose a large portion of its crust, present to us earlier 

 forms of organic life, which have now almost entirely disap- 

 peared ; and these forms are associated in groups, successively 

 replacing each other. The different superimposed strata thus 

 present to us the buried faunas and floras of different 

 epochs. In this sense the description of nature cannot be 

 separated from its history ; for, in studying the present, the 

 geologist, in tracing the mutual relations of thefactswhich come 

 before him, is conducted back to ages long past : this inter- 

 mixture of past and present is in some respects analogous to 

 that which may be observed in the study of languages, where 

 the etymologist fmdstraces of successive grammatical develop- 

 ments, leading him back to the primitive state of the 

 idiom reflected as it were in forms of speech now in use. 

 In the material world, this reflex of the past is the clearer, 

 from our now seeing similar eruptive and sedimentary rocks 

 in process of formation. The particular forms of domes of 

 trachyte, basaltic cones, bauds of amygdaloid with long 

 parallel pores, and white deposits of pumice with black 

 scoriae intermixed, give in the eye of the geologist a pecu- 

 liar kind of animation to the landscape, acting on his ima- 

 gination as traditional monuments of an earlier world. Their 

 form is their history. 



The sense in which the Greeks and Romans employed the 



