Introductory. 7 
in order to have any question to put to the test of 
objective verification, science must already have so far 
employed the method of speculation as to have framed 
a question to be tested ; and, secondly, that the point 
where science parts company with speculation is the 
point where this testing process begins. 
Now, if these things are so, there can be no doubt 
that Darwin was following the truest method of induc- 
tive research in allowing any amount of latitude to his 
speculative thought in the direction of scientific theo- 
rizing. For it follows from the above distinctions that 
the danger of speculation does not reside in the width 
of its range, or even in the impetuosity of its vehe- 
mence. Indeed, the wider its reach, and the greater its 
energy, the better will it be for the interests of science. 
The only danger of speculation consists in its momen- 
tum being apt to carry away the mind from the more 
laborious work of adequate verification; and therefore 
a true scientific judgment consists in giving a free 
rein to speculation on the one hand, while holding 
ready the break of verification with the other. Now, 
it is just because Darwin did both these things with 
so admirable a judgment, that he gave the world of 
natural history so good a lesson as to the most effec- 
tual way of driving the chariot of science. 
This lesson we have now all more or less learnt to 
profit by. Yet no other naturalist has proved himself | 
so proficient in holding the balance true. For the 
most part, indeed, they have now all ceased to con- 
found the process of speculation per se with the danger 
of inadequate verification ; and thcrefore the old ideal 
of natural history as concerned merely with collecting 
species, classifying affinities, and, in general, tabulating 
