450 THE CAUSES OF THE Xl 
admit the objection, that it is preposterous to 
trouble ourselves about the history of the Roman 
Empire, because we do not know anything positive 
about the origin and first building of the city of 
Rome! Would it be a fair objection to urge, 
respecting the sublime discoveries of a Newton, or 
a Kepler, those great philosophers, whose dis- 
coveries have been of the profoundest benefit and 
service to all men—to say to them— After all 
that you have told us as to how the planets re- 
volve, and how they are maintained in their orbits, 
you cannot tell us what is the cause of the origin 
of the sun, moon, and stars. So what is the use 
of what you have done?” Yet these objections 
would not be one whit more preposterous than 
the objections which have been made to the 
“Origin of Species.” Mr. Darwin, then, had a 
perfect right to limit his inquiry as he pleased, 
and the only question for us—the inquiry being 
so limited—is to ascertain whether the method of 
his inquiry is sound or unsound ; whether he has 
obeyed the canons which must guide and govern 
all investigation, or whether he has broken 
them; and it was because our inquiry this 
evening is essentially limited to that question, 
that I spent a good deal of time in a former 
lecture (which, perhaps some of you thought 
might have been better employed), in endeavour- 
ing to illustrate the method and nature of scien- 
tific inquiry in general, We shall now have to 
