ON THEORIES OF THE EARTH. 



tiality is not the result of this profession ; excess of 

 ardour is more than compensated by prejudices : the 

 path of observation is not the less crooked ; and, to 

 disclaim theory, is the most pernicious of theories. 

 But this is to waste words on a fundamental ignorance 

 of the very nature of philosophy : in any other science, 

 I might have spared even these remarks. In none can 

 the very work of observation proceed without general 

 principles; without theory. Not understood, facts are 

 useless; but, not understood, they are not even seen. 

 He who knows what to see, sees: and, without know- 

 ledge, the man and the quadruped, equally seeing, see 

 to the same purpose. And if we are ever to wait for 

 future discoveries, the result is, that we neither know 

 what we want, nor where to seek, nor how to use what 

 we may have obtained. 



Nor can any collector of facts advance long on his 

 principle of purity. He must soon discover some link 

 which unites many; and from that moment he is a 

 theorist. Under new anomalies, there must be new 

 approximations, the impossible quantities are gradually 

 elicited from his equation, and if he does not become 

 what he disclaims, it is time that he should retire, since 

 he has as much mistaken his talents as he is ignorant 

 of philosophy. The path which he scorns will ulti- 

 mately terminate in a just theory; while the purist in 

 facts is heaping up rubbish ; a mark for avoidance. If 

 I ought not to have a reader capable of believing that 

 theory can be opposed to facts, so do I not write for 

 him who can confound theory with hypothesis. The 

 spirit of system, in the latter, is a false and misleading 

 one: in the former, it is the animating principle. The 

 theory which is deduced from facts is ever improving 

 under new ones : the hypothesis which stands this test 

 long, will be more fortunate than its predecessors. If 



