XI PHENOMENA OF ORGANIC NATURE 375 



two hypotheses. That one which is based on 

 sound scientific knowledge is sure to have a corre- 

 sponding 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, naturally 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 pro- 

 portionate 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 prac- 

 tical 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 verification. 



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 import- 

 ant for you to understand than the mental pro- 

 cesses and the means by which we obtain scientific 



