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 chat 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 chat 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 chat 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 the
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 (sitta Europaea), which live much
on hazel nuts; and yet they open them each in a different way. The