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 
auses 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 
ientific hypothesis; and its value will be pro- 
portionate to the care and completeness with which 
these matters as in the commonest affairs of prac- 
al life: the guess of the fool will be folly, while 
‘depends onthe 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 foakin 
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 
