Chap. IV. Moral Sense. 107 



mankind, selfishness, experience, and imitation, probably add, 

 as Mr. Bain has shewn, to the power of sympathy ; for we are 

 led by the hope of receiving good in return to perform acts 

 of sympathetic kindness to others; and sympathy is much 

 strengthened by habit. In however complex a manner this 

 feeling may have originated, as it is one of high importance to 

 all those animals which aid and defend one another, it will have 

 been increased through natural selection ; for those commu- 

 nities, which included the greatest number of the most sympa- 

 thetic members, would flourish best, and rear the greatest 

 number of offspring. 



It is, however, impossible to decide in many cases whether 

 certain social instincts have been acquired through natural 

 selection, or are the indirect result of other instincts and 

 faculties, such as sympathy, reason, experience, and a tendency 

 to imitation ; or again, whether they are simply the result of 

 long-continued habit. So remarkable an instinct as the placing 

 sentinels to warn the community of danger, can hardly have 

 been the indirect result of any of these faculties ; it must, there- 

 fore, have been directly acquired. On the other hand, the habit 

 followed by the males of some social animals of defending the 

 community, and of attacking their enemies or their prey in 

 concert, may perhaps have originated from mutual sympathy ; 

 but courage, and in most cases strength, must have been 

 previously acquired, probably through natural selection. 



Of the various instincts and habits, some are much stronger 

 than others ; that is, some either give more pleasure in their 

 performance, and more distress in their prevention, than others ; 

 or, which is probably quite as important, they are, through 

 inheritance, more persistently followed, without exciting any 

 special feeling of pleasure or pain. We are ourselves conscious 

 that some habits are much more difficult to cure or change than 

 others. Hence a struggle may often be observed in animals 

 between different instincts, or between an instinct and some 

 habitual disposition; as when a dog rushes after a hare, is 

 rebuked, pauses, hesitates, pursues again, or returns ashamed to 

 his master ; or as between the love of a female dog for her young 

 puppies and for her master,— for she may be seen to shnk away 

 to them, as if half ashamed of not accompanying her master. 

 But the most curious instance known to me of one instinct 

 getting the better of another, is the migratory instinct conquer- 

 uig the maternal instinct. The former is wonderfully strong; a 

 confined bird will at the proper season beat her breast against 

 the wires of her cage, until it is bare and bloody. It causes 

 young salmon to leap out of the fresh water, in which they could 



