COSMIC PHILOSOPHY 



astronomy depends upon that of terrestrial phy- 

 sics, and should therefore come after, and not 

 before it. In fact the whole science of astro- 

 nomy, as at present constituted, consists of two 

 portions, — the theory of gravitation and the 

 theory of nebular evolution. The first of these, 

 as we have just seen, is a mere extension to 

 celestial phenomena of certain laws of terrestrial 

 physics. The second depends upon the study 

 of terrestrial phenomena in a yet greater de- 

 gree, since it involves the knowledge not only 

 of gravitation, but also of radiant heat, and of 

 the conditions of equilibrium of gases and 

 liquids. 1 



If now we compare physics with chemistry, 

 we shall find a similar ambiguity in Comte's 

 results. It is easy to say that chemistry was 

 not organized into a science until toward the 

 close of the eighteenth century, while physics 

 was organized at the beginning of the seven- 



i I leave this as it stood five years ago, when this chapter 

 was written. The numerous and wonderful disclosures of 

 spectrum analysis, not only giving us unlooked-for information 

 concerning the physical constitution of the stars, but even throw- 

 ing new light on their movements, make it desirable, perhaps, 

 to enlarge the scope assigned to astronomy in the text. But 

 such a modification of the form of statement would show only 

 the more forcibly how closely the study of astronomy depends 

 on the study of terrestrial phenomena. The greatest step re- 

 cently taken in science is thus an additional argument against 

 the validity of Comte's conception. 

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