LETTER LVI 



TO THE SAME 



THEY who write on natural history cannot too fre- 

 quently 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 appear- 

 ance, nor is it so beautifully studded with lichens, as in a 

 more rural district : and the wren is obliged to construct 

 it's house with straws and dry grasses, which do not give it 

 that rotundity and compactness so remarkable in the edi- 

 fices 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 



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