It is only in particulars that instinct appears superior to reason in the works it achieves. When an animal is taken, ever so little, out of the ordinary circumstances in which its instincts act, it is apt to behave very foolishly. If a woodpecker's egg is hatched by a bird which builds an open nest upon the branches of a tree, when the young bird is grown large enough to shuffle about in the nest, induced by its instinct to suppose that its nest is in a hole walled round on all sides by the tree, with a long, narrow entrance down from above, it does not see that it has been inducted into the open nest of another bird, and is sure to tumble out. The bee and the ant, in a few particulars, show wonderful sagacity; but remove them from the narrow compass of their instincts, and all their wisdom is at an end. That animals are so wise in a few things and so wanting in wisdom in all others shows that they are endowed with a mental principle essentially of a different nature from that of the human race. "They do many things even better than ourselves," says Descartes; "but this does not prove them to be endowed with reason, for this would prove them to have more reason than we have, and that they should excel us in all other things also"; for reason can act not only in one direction, but in all. But it will be said that instinct is not invariable,--that it often displays a capacity of accommodating itself, like reason, to circumstances, and is therefore a principle the same in kind with it,--or else that the animal has something of the rational faculty superadded to the instinctive. But does the animal make these variations in its conduct from a true perception of their meaning and purpose?