828 THE POPULAR SCIEN.CE MONTHLY. 



Viewed in the light of evolution, a law of nature is merely the 

 most generalized expression for a particular occurrence of phenomena. 

 Take, for instance, the law of the conservation of energy: observation, 

 long continued, shows that with whatsoever objects we deal, and-how- 

 ever we may apparently destroy the energy contained in them, yet 

 closer observation, with more accurate instruments, will discern that 

 the energy previously visible has only disappeared to reappear in an- 

 other form. Finding the same result in every case to which we are 

 able to apply our tests, and discovering no exception to the rule, we 

 abstract the particular objects we have been considering, and, confin- 

 ing our attention to the persistence of energy which each displays, 

 group this class of phenomena into one category and exj)ress the like- 

 ness by the law that energy endures. 



Each deduction from a law is a separate verification of its truth, and 

 as these verifications increase in number the probability of finding an 

 exception decreases. Hence, the law soon assumes a form of necessity 

 as different as possible from its original character. Add to this that 

 many of the laws of nature have only to be expressed to be admitted 

 laws whose concretes were objects of observation to our earliest an- 

 cestors away back in the youth of life upon our globe, and are, to us 

 at least, intuitive and we see how natural the attribution of necessity 

 to them appears. Besides this, the word law conveys a meaning en- 

 tirely outside its scientific acceptation. As popularly used it expresses 

 the command of a ruler ; and this civil or theological meaning, as ap- 

 plied to the laws of nature, is continually being brought to scientific 

 discussions, much to the detriment of their clearness. Mathematics 

 alone among the sciences has been able to keep clear of these danger- 

 ous alliances, and we there still see the word used in its properly scien- 

 tific application as an order of sequence merely. Although mathemati- 

 cal. law is not coextensive with physical law, it is this meaning which 

 we should endeavor to preserve. The word is an unfortunate one at 

 best, and some philosophers and scientists have advocated its disuse and 

 the substitution of some more accurate term ; but it is too deeply rooted 

 in scientific language for that, and we can only enter a protest against 

 its use in scientific discussions in other than a scientific sense. We 

 have only to consider the scientific genesis of the term to obtain a rule 

 for its application. Considered merely as the generalized expression 

 of the result of observation, we clearly perceive that, however long 

 these observations may have continued, they carry with them no neces- 

 sity except in so far as relates to our own organism. It is just here 

 that the idea of necessity asserts its power. Take the most funda- 

 mental law of mechanics, or even (for the supposed necessity in each 

 case arises in the same way) one of the primary axioms of mathe- 

 matics, and, by an analysis of the genesis of these conceptions, we 

 shall, with the aid of the light that the theory of evolution sheds into 

 those obscure recesses of the mind where consciousness is coming into 



