XIII CONTRIVANCES OF AQUATIC INSECTS 389 



so much benevolent foresight can be reconciled 

 with so much cruelty, it is not for the naturalist to 

 explain, though the mere naturalist finds it hard to 

 shake off these thoughts when they have once come 

 up in his mind. 



The beginnings of mercy and unselfishness appear 

 in the behaviour of wild animals to their young. 

 Social animals are called upon for a more habitual 

 exercise of the same attributes, and it is perhaps the 

 social state which has chiefly moderated the selfish- 

 ness of Man ; it is the social instinct which leads 

 him to pity even the humblest victims of the struggle 

 for existence. 



When we have to tell what we have seen and found, 

 it is our business to give a true account, disguising 

 nothing, and keeping nothing back. But let us be 

 careful not to speak as if our little plummets had 

 sounded the depths of the universe. Those who have 

 surpassed their fellows in the improvement of natural 

 knowledge, have always been the first to admit that 

 what they have come to know is lost in the infinitude 

 of the unknown. 



