LETT EROXXViIL 
ON THE INSTINCT OF INSECTS. 
THE greater part of those surprising facts connected 
with the manners and economy of insects, of which the 
relation has occupied the preceding letters, is to be re- 
ferred, I have told you, to their instinct. But what, you 
will ask, is this instinct ?—of what nature is this faculty 
which produces effects so extraordinary ? 
To this query I do not pretend to give any satisfac- 
tory answer. As Iam quite of Bonnet’s opinion, that 
philosophers will in vain torment themselves to define 
instinct, until they have spent some time in the head of 
an animal without actually beng that animal—a species 
of metempsychosis through which I have never passed— 
I shall not attempt to explain what this mysterious ener- 
gy is. It will not, however, I imagine, be very difficult 
to show what it is not; and some observations with this 
view, followed by an enumeration of peculiarities which 
distinguish the instincts of insects from those of other 
tribes of animals, and a short inquiry whether their ac- 
tions are guided solely by instinct, will form the substance 
of this letter. 
