116 Evolution and Adaptation 
vince us of our ignorance on the mutual relations of all 
organic beings; a conviction as necessary, as it is difficult, 
to acquire. All that we can do, is to keep steadily in mind 
that each organic being is striving to increase in a geometri- 
cal ratio; that each at some period of its life, during some 
season of the year, during each generation or at intervals, 
has to struggle for life and to suffer great destruction. When 
we reflect on this struggle, we may console ourselves with the 
full belief, that the war of nature is not incessant, that no 
fear is felt, that death is generally prompt, and that the vig- 
orous, the healthy, and the happy survive and multiply.” 
The kindliness of heart that prompted the concluding sen- 
tence may arouse our admiration for the humanity of the 
writer, but need not, therefore, dull our criticism of his theory. 
For whether no fear is felt, and whether death is prompt or 
slow, has no bearing on the question at issue — except as it 
prepares the gentle reader to accept the dreadful calamity of 
nature, pictured in this battle for existence, and make more 
contented with their lot “the vigorous, the healthy, and the 
” 
happy. 
THE THEORY OF NATURAL SELECTION 
We have already anticipated, to some extent, Darwin’s 
conclusion in regard to the outcome of the competition of 
animals and plants. This result is supposed to lead to the 
survival of the fittest. The competition is carried out by 
nature, who is personified as selecting those forms for further 
experiments that have won in the struggle for existence. 
“Can the principle of selection, which we have seen is so 
potent in the hands of man, apply under Nature? I think 
we shall see that it can act most efficiently. Let the endless 
number of slight variations and individual differences occur- 
ring in our domestic productions, and, in a lesser degree, in 
those under Nature, be borne in mind; as well as the strength 
of the hereditary tendency. Can it, then, be thought im- 
