€hap. III. 
MORAL SENSE. 
83 
the indirect result of any other faculty ; 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 more persistently followed through 
inheritance without exciting any special feeling of plea- 
sure 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 slink away to them, 
as if half ashamed of not accompanying her master. 
But the most curious instance known to me of one 
instinct conquering another, is the migratory instinct 
conquering the maternal instinct. The former is won- 
derfully 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, where they could still continue to 
live, and thus unintentionally to commit suicide. Every 
one knows how strong the maternal instinct is, leading 
even timid birds to face great danger, though with 
hesitation and in opposition to the instinct of self- 
a 2 
