THE AIM OF SCIENCE 49 



e. g. of its development. For that requires a 

 historical explanation. 



LAWS OF NATURE. If Science is only de- 

 scription, what is to be said of the Laws of 

 Nature, which Science has discovered, which, 

 moreover, things used to "obey," when we were 

 at school? Let us find an answer to this question 

 in the words of a keen investigator, who, having 

 helped to make physical laws, should know some- 

 thing about them. "We must confess," says 

 Prof. J. H. Poynting, "that physical laws have 

 greatly fallen off in dignity. No long time ago 

 they were quite commonly described as the Fixed 

 Laws of Nature, and were supposed sufficient in 

 themselves to govern the universe. Now we 

 can only assign to them the humble rank of 

 mere descriptions, often erroneous, of similar- 

 ities which we believe we have observed" (Ad- 

 dress, British Association, 1889, p. 616). 



Prof. Poynting goes on to say that a "law 

 of nature explains nothing it has no govern- 

 ing power, it is but a descriptive formula which 

 the careless have sometimes personified. There 

 may be psychological and social generalizations 

 which really tell us why this or that occurs, but 

 chemical and physical generalizations are wholly 

 concerned with the how." 



In other words, concurrently with the change 

 in our conception of physical law has come a 



