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that some animals are born with instincts perfect for the 
work they have to do ; and other animals with imperfectly 
developed instincts or mere instinctive tendencies. It ac 
counts for the failure of instinct when the animal is placed 
in a sphere of which its race has had no experience. 
It justifies us in expecting a new development of instinct, 
no less than new modifications of structure, to meet the 
exigencies of new conditions. 
In the second place we venture to assume that some 
animals are intelligent and that their actions are sometimes 
under the surveillance of their intelligence. It might be 
difficult to prove that this was the case in some instances ; 
as when, for example, animals are born with perfect instincts 
which never require to be modified in the face of unchanged 
conditions. But it is obvious that different animals are 
born in different stages of development, both of organism 
and of instinct. The bird which is hatched in a nest built 
in a tree is at first utterly helpless and completely de 
pendent upon its parents. The bird that is hatched in 
a nest on the ground could not escape destruction unless it 
were endowed with fully-developed powers of locomotion 
and an instinctive knowledge of its parents’ cries of 
warning or of invitation. 
The power of the animal to correct its innate tendencies 
of itself and to receive instruction from others, no less than 
the power to impart instruction, implies a certain amount 
of intelligence, and should serve to convince us, without 
any elaborate argument, that animal experience is made 
up of instinct and of intelligence. It is unnecessary for 
my present purpose to enter at large into any proof that 
all the actions of all animals are purely instinctive and 
non-intelligent. In face of the simplest act of animal in 
telligence, I refuse to bow to the dictum of utter scepticism 
expressed by Bonnet, when he asserts that “ philosophers 
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