60 METHOD OF DISCOVERY. 



the ultimate conclusion, and he disputes the question 

 no further. He sees that the experiment has been 

 tried under all sorts of conditions, as to time, place, 

 and people, with the same result ; and he says with 

 you, therefore, that the law you have laid down must 

 be a good one, and he must believe it. 



In science we do the same thing ; — the philosopher 

 exercises precisely the same faculties, though in a much 

 more delicate manner. In scientific inquiry it becomes 

 a matter of duty to expose a supposed law to every 

 possible kind of verification, and to take care, more- 

 over, that this is done intentionally, and not left to a 

 mere accident, as in the case of the apples. And in 

 science, as in common life, our confidence in a law is 

 in exact proportion to the absence of variation in the 

 result of our experimental verifications. For instance, 

 if you let go your grasp of an article you may have in 

 your hand, it will immediately fall to the ground. That 

 is a very common verification of one of the best estab- 

 lished laws of nature — that of gravitation. The method 

 by which men of science establish the existence of that 

 law is exactly the same as that by which we have estab- 

 lished the trivial proposition about the sourness of hard 

 and green apples. But we believe it in such an exten- 

 sive, thorough, and unhesitating manner because the 

 universal experience of mankind verifies it, and we can 

 verify it ourselves at any time ; and that is the strongest 

 possible foundation on which any natural law can rest. 



So much by way of proof that the method of estab- 

 lishing laws in science is exactly the same as that pur- 

 sued in common life. Let us now turn to another 

 matter (though really it is but another phase of the 

 same question), and that is, the method by which, from 



