INTRODUCTORY. 9 
pensates in some degree for the terrible mischief 
which it causes in other ways. 
So it often is with Nature, who, at one and the same 
time, is an open enemy and a secret friend. Visibly 
she strives against us; invisibly she aids us. What 
she takes with one hand in the view of all, she 
restores, often immeasurably augmented, as it were 
surreptitiously with the other. She resents man’s 
interference with her arrangements, and resents it 
bitterly, and yet she assists him in ways many and 
various to carry that interference to a successful con- 
clusion. And man, carelessly ignorant of all that 
with which he is not actually brought face to face, 
sees only the evil and passes by the good, and the 
years roll by and leave him still imbued with the 
almost superstitious prejudices of his forefathers, 
working against his own interests with all his ener- 
gies, and blind to aught that might convince him of 
his mistakes. 
An animal helps him throughout its life, and he 
persecutes it to the utmost of his power. Another 
injures him seriously, and he kills off the creatures 
which Nature has appointed to restrain its increase 
within due limits. And thus his life and labour 
form one long opposition to natural laws, and he 
persistently strives, by every practicable means, both 
to increase the already numerous difficulties which 
beset him, and to alienate or even altogether destroy 
the very beings by whose assistance alone he can 
hope to win the victory. 
It is frequently urged, and with much apparent 
