OF NATURAL PHILOSOPHY. 175 



enquiry demands continually the alternate use of 

 both the inductive and deductive method. The path 

 by which we rise to knowledge must be made smooth 

 and beaten in its lower steps, and often ascended and 

 descended, before we can scale our way to any emi- 

 nence, much less climb to the summit. The achieve- 

 ment is too great for a single effort ; stations must 

 be established, and communications kept open with 

 all below. To quit metaphor ; there is nothing so 

 instructive, or so likely to lead to the acquisition of 

 general views, as this pursuit of the consequences of 

 a law once arrived at into every subject where it 

 may seem likely to have an influence. The dis- 

 covery of a new law of nature, a new ultimate fact, 

 or one that even temporarily puts on that appear- 

 ance, is like the discovery of a new element in che- 

 mistry. Thus, selenium was hardly discovered by 

 Berzelius in the vitriol works of Fahlun, when it 

 presently made its appearance in the sublimates of 

 Stromboli, and the rare and curious products of the 

 Hungarian mines. And thus it is with every new 

 law, or general fact. It is hardly announced before 

 its traces are found every where, and every one is 

 astonished at its having so long remained concealed. 

 A.nd hence it happens that unexpected lights are 

 shed at length over parts of science that had been 

 abandoned in despair, and given over to hopeless 

 obscurity. 



(185.) The verification of quantitative laws has 

 been already spoken of (178.) ; but their importance in 

 physical science is so very great, inasmuch as they 

 alone afford a handle to strict mathematical deduc- 

 tive application, that something ought to be said of 



