Introductory. 5 
distinction clearly in view, his idea of the scientific use | 
of facts is plainly that of furnishing legitimate material | 
for the construction of theories. Natural history is 
not to him an affair of the herbarium or the cabinet. 
The collectors and the species-framers are, as it were, 
his diggers of clay and makers of bricks: even the 
skilled observers and the trained experimentalists are 
his mechanics, Valuable as the work of all these men , 
is in itsclf, its principal value, as he has finally de- | 
monstrated, is that which it acquires in rendering 
possible the work of the architect. Therefore, although 
he has toiled in all the trades with his own hands, and 
in each has accomplished some of the best work that 
has ever been done, the great difference between him 
and most of his predecessors consists in this,—that 
while to them the discovery or accumulation of facts 
was an end, to him it is the means. In their eyes it 
was enough that the facts should be discovered and 
recorded. In his eyes the value of facts is due to 
their power of guiding the mind to a further discovery 
of principles. And the extraordinary success which 
attended his work in this respect of generalzzation 
immediately brought natural history into line with the 
other inductive sciences, behind which, in this most 
important of all respects, she has so seriously fallen. 
For it was the Origin of Species which first clearly 
revealed to naturalists as a class, that it was the duty 
of their science to take as its motto, what is really the - 
moito of natural science in general, 
Felix qui potuit rerum cognoscere causas. 
Not facts, then, or phenomena, but causes or prin- 
ciples, are the ultimate objects of scientific quest. It 
remains to ask, How ought this quest to be prosecuted ? 
