Chap. XIV. 
RECAPITULATION. 
459 
CHAPTEE XIY. 
Recapitulation and Conclusion. 
Recapitulation of the difficulties on the theory of Natural Selection 
'— Recapitulation of the general and special circumstances in its 
favour — Causes of the general belief in the immutability of 
species—-How far the theory of natural selection may be 
extended — Effects of its adoption on the study of Natural 
history — Concluding remarks. 
As this whole volume is one long argument, it may be 
convenient to the reader to have the leading facts and 
inferences briefly recapitulated. 
That many and serious objections may be advanced 
against the theory of descent with modification through 
natural selection, I do not deny. I have endeavoured 
to give to them then: full force. Nothing at first can 
appear more difficult to believe than that the more 
complex organs and instincts should have been per¬ 
fected, not by means superior to, though analogous 
with, human reason, but by the accumulation of innumer¬ 
able slight variations, each good for the individual pos¬ 
sessor. Nevertheless, this difficulty, though appearing 
to our imagination insuperably great, cannot be con¬ 
sidered real if we admit the following propositions, 
namely,—that gradations in the perfection of any .organ 
or instinct which, we may consider, either do now exist 
or could have existed, each good of its kind,—that all 
organs and instincts are, in ever so slight a degree, 
variable,—and, lastly, that there is a struggle for exist¬ 
ence leading to the preservation of each profitable 
deviation of structure or instinct. The truth of these 
propositions cannot, I think, be disputed, 
X 2 
