66 METHOD OF DISCOVERY. 



enormous difference in the value of the two hypotheses. 

 That one which is based on sound scientific knowledge 

 is sure to have a corresponding value ; and that which 

 is a mere hasty random guess is likely to have but little 

 value. Every great step in our progress in discovering 

 causes has been made in exactly the same way as that 

 which I have detailed to you. A person observing the 

 occurrence of certain facts and phenomena asks, natu- 

 rally enough, what process, what kind of operation 

 known to occur in nature applied to the particular 

 case, will unravel and explain the mystery? Hence 

 you have the scientific hypothesis : and its value will 

 be proportionate to the care and completeness with 

 which its basis had been tested and verified. It is in 

 these matters as in the commonest affairs of practical 

 life : the guess of the fool will be folly, while the guess 

 of the wise man will contain wisdom. In all cases, 

 you see that the value of the result depends on the 

 patience and faithfulness with which the investigator 

 applies to his hypothesis every possible kind of verifi- 

 cation. 



I dare say I may have to return to this point by- 

 and-by ; but having dealt thus far with our logical 

 methods, I must now turn to something which, perhaps, 

 you may consider more interesting, or, at any rate, 

 more tangible. But in reality there are but few things 

 that can be more important for you to understand than 

 the mental processes and the means by which we obtain 

 scientific conclusions and theories.* Having granted 

 that the inquiry is a proper one, and having determined 



* Those who wish to study fully the doctrines of which I have en- 

 deavoured to give some rough and ready illustrations, must read Mr. John 

 Stuart Mill's " System of Logic." 



