.226 THE NATURAL HISTORY OF SELBORNE. — 
might be found there, in different secret dormitories; and that, 
so far from withdrawing into warmer climes, it would appear 
that they never depart three hundred yards from the village. 
LETTER ds 
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 compelled 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 schoolboy 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 
remarkable in the edifices of that little architect. Again, the 
regular nest of the house-martin is hemispheric; but where a 
rafter, or a joice, 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 compressed. 
