68 METHOD OF DISCOVERY. 



man goes through in tracing the causes of natural phe- 

 nomena. 



A very trivial circumstance will serve to exemplify 

 this. Suppose you go into a fruiterer's shop, wanting 

 an apple, — you take up one, and, on biting it, you find 

 it is sour ; you look at it, and see that it is hard and 

 green. You take up another one, and that too is hard, 

 green, and sour. The shopman offers you a third ; 

 but, before biting it, you examine it, and find that it is 

 hard and green, and you immediately say that you 

 w T ill not have it, as it must be sour, like those that you 

 have already tried. 



Nothing can be more simple than that, you think ; 

 but if you will take the trouble to analyze and trace 

 out into its logical elements what has been done by 

 the mind, you will be greatly surprised. In the first 

 place, you have performed the operation of Induc- 

 tion. You found that, in two experiences, hardness 

 and greenness in apples go together with sourness. It 

 was so in the first case, and it was confirmed by the 

 second. True, it is a very small basis, but still it is 

 enough to make an induction from ; you generalize 

 the facts, and you expect to find sourness in apples 

 where you get hardness and greenness. You found 

 upon that a general law, that all hard and green apples 

 are sour ; and that, so far as it goes, is a perfect induc- 

 tion. Well, having got your natural law in this way, 

 when you are offered another apple which you find is 

 hard and green, you say, " All hard and green apples 

 are sour ; this apple is hard and green, therefore this 

 apple is sour." That train of reasoning is what logi- 

 cians call a syllogism, and has all its various parts and 

 terms, — its major premiss, its minor premiss, and its 



