THE LIMITS OF NATURAL SELECTION, ETO, 333 
excite some surprise among my readers, to find that 
I do not consider that all nature can be explained on 
the principles of which I am so ardent an advocate ; 
and that I am now myself going to state objections, 
and to place limits, to the power of “ natural selection.” 
I believe, however, that there are such limits; and that 
just as surely as we can trace the action of natural 
laws in the development of organic forms, and can 
clearly conceive that fuller knowledge would enable 
us to follow step by step the whole process of that 
development, so surely can we trace the action of 
some unknown higher law, beyond and independent 
of all those laws of which we have any knowledge. 
We can trace this action more or less distinctly in 
' many phenomena, the two most important of which 
are—the origin of sensation or consciousness, and the 
development of man from the lower animals. I shall 
first consider the latter difficulty as more immediately 
-connected with the subjects discussed in this volume. 
What Natural Selection can Not do. 
In considering the question of the development of 
man by known natural laws, we must ever bear in 
mind the first principle of “natural selection,” no less 
than of the general theory of evolution, that all changes 
of form or structure, all increase in the size of an 
organ or in its complexity, all greater specialization or 
physiological division of labour, can only be brought 
about, in as much as it is for the good of the being 
so modified. Mr. Darwin himself has taken care to 
