EXAMPLES OF THE EXPLANATION OF LAWS. 277 



process with wliicb we are here concerned often does the very con- 

 trary; it resolves a phenomenon with which we ai-e famiHar, into one 

 of which we previously- knew little or nothing; as when the connnon 

 fact of the fall of ht:avy bodies is resolved into a tendency of all par- 

 ticles of matter towards oiu- another. It must be kept constantly in^ 

 view, therefore, that wIumi j)hilosophers speak of explaining any of 

 the phenotneua of nature, they always mean, pointing out not some 

 more familiar but merely some more general phenomenon -of which it 

 is a p;utial exempliHcatiou, or some laws of causation which produce 

 it by their joint or successive action, and from which, therefore, its 

 conditions may be determined deductively. Every such operation 

 brings us a step nearer towards answering the question, which was 

 stated some time agO as comprehending the whole problem of the 

 investigation of nature viz., What are the fewest a.ssumptions which 

 being gianted, the order of nature as it exists would be the result 1 

 Wliat are tlxe fewest general ]iropositions from which all the uniformities 

 existing in natui-e could be deduced I 



The laws, thus explained or resolved, are sometimes said to be 

 accou/ited Jor ; but the expression is incon-ect, if taken to mean any- 

 thing more than what has been already stated. In minds not habituated 

 to accurate thinking, there is often' a confused notion that the general 

 laws are the causas of the partial ones ; that the law of general gravita- 

 tion, for example, causes the jjhenomenon of the fall of bodies to the 

 earth. But to assert this, would be a misuse of the word cause : 

 ten'estrial gi'avity is not an effect of general gravitation, btit a case of 

 it ; tliat is, one kind of the particular instances in which that general 

 law obtains. To account for a law of nature means, and can mean, no 

 more than to assign other laws more general, together with collocations, 

 which laws and collocations being supposed, the partial law follows 

 without any additional supposition. 



CHAPTER XIII. 



MISCELLANEOUS EXAMPLES OF THE EXPLANATION OF LAWS OF NATURE. 



§ 1. So MR of the most remarkable instances which have occurred 

 since the great Newtonian generahaation, of the explanation of laws 

 of causation subsisting among complex phenomena, by resolving them 

 ijito simpler and more general laws, are to be found among the recent 

 speculatirjns of Liebig in organic chemistry. These speculationSi 

 although they have not yet been sufficiently loflg before the world to 

 entitle ns positively to assume that no well-grounded objection can be 

 made to any part of them, aflbrd, however, so admirable an example 

 of the spirit of the Deductive Method, that I may be permitted to pre- 

 sent some Bjjccimens of them here. 



It had been observed in certain cases, that chemical action is, as it 

 were, contagious ; that is to say, a substance which would n<»t of itself 

 yield to a particular chemical attraction, (tl»e force of the attraction 

 not being sufficient to overcome cohfcjHou, or to destroy some chemical 

 combination in which the substanpe waa aheady held,) will neverthc- 



