110 NATtJRAL IirsTORir 



LETTER LVI. 



TO THE SAME. 



They who write on natural history can- 

 not too frequent advert to instinct, that 

 wonderful limited faculty, which, in some 

 instances, raises the brute creation as it 

 were. above reason, and in others leaves 

 them so far below it. Philosophers have 

 defined instinct to be that secret influence 

 by which every species is impelled natu- 

 rally to pursue, at all times, the same 

 way or track, without any teaching or ex- 

 ample ; whereas reason, without instruction, 

 would often vary and do that by many 

 methods which instinct effects by one alone. 

 Now thi s maxim must be taken in a qualified 

 sense ; for there are instances in which m- 

 stinct does vary and conform to the circum- 

 stances of place and convenience.. 



It has been remarked that every species 

 of bird has a mode of nidifi cation peculiar 



