of Selborne 231 



LETTER LVI 



TO THE HONOURABLE DAINES HARRINGTON 



They who write on natural history cannot too frequently 

 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 naturally to 

 pursue, at all times, the same way or track, without any 

 teaching or example ; whereas reason, without instruction, 

 would often vary and do that by many methods which 

 instinct effects by one alone. Now this maxim must be 

 taken in a qualified sense ; for there are instances in 

 which instinct does vary and conform to the circumstances 

 of place and convenience. 



It has been remarked that every species of bird has a 

 mode of nidification peculiar to itself; so that a school- 

 boy would at once pronounce on the sort of nest before 

 him. This is the case among fields and woods, and 

 wilds ; but, in the villages round London, where mosses 

 and gossamer, and cotton from vegetables, are hardly to 

 be found, the nest of the chaffinch has not that elegant 

 finished appearance, nor is it so beautifully studded with 

 lichens, as in a more rural district : and the wren is obliged 

 to construct its house with straws and dry grasses, which 

 do not give it that rotundity and compactness so remark- 

 able in the edifices of that little architect. Again, the 

 regular nest of the house-martin is hemispheric ; but 

 where a rafter, or a joist, or a cornice may happen to 

 stand in the way, the nest is so contrived as to conform 

 to the obstruction, and becomes flat or oval, or compressed. 



In the following instances instinct is perfectly uniform 

 and consistent. There are three creatures, the squirrel, 

 the field-mouse, and the bird called the nut-hatch {siifa 

 EiiropcEo), which live much on hazel nuts ; and yet they 

 open them each in a difi"erent way. The first, after rasp- 



