XXXVI.] PERCEPTION. 127 



Berkeley, however, left imsolved, and I believe unat- 

 tempted, the real difficulty of his theory. I mean that con- Difficulty 

 cernin<j[ the instinctive motor actions of animals. Young i'^'^^?* 



lllStlllC- 



ducks, for instance, run to the water and begin to swim tive 

 as soon as they leave the egg; so that we see them able aTuck' ^'* 

 to perform, without having learned, actions of the same ranning to 

 character as those which a child performs in consequence when It" 

 of having learned, such as walking or feeding itself. ISTow, ^®^^^^ ^^^ 

 the actions of young ducks, and of most young animals, 

 evidently involve perception, and are a result of it. What 

 then becomes of Berkeley's theory, that the perception of 

 objects has to be learned? To state the argument more 

 clearly : — The young duck knows — not consciously, but in 

 an unconscious way that serves it for guidance — that the 

 water which it sees is water in which it can swim. It 

 leaves the egg, not only witli the same power of sensation 

 which man possesses at birth, but also with that power of 

 perception which, if Berkeley's analysis of perception is 

 correct, man only acquires gradually and by experience. 

 It is no explanation to say that animals are instinctive, 

 but man is rational. We have no ground for thinking 

 that there is any fundamental difference between instinct 

 and reason ; or, since the words instinct and reason have 

 acquired misleading associations, I will say rather between 

 the animal powers of mind and the lower human ones. 



In this state the question was left by Berkeley ; and 

 Mill, in a review on the subject, which was first published 

 more than twenty years ago, after stating with his usual 

 ability the grounds for believing that we have no possible 

 means, except experience, for identifying the objects of 

 sight with the objects of touch, concluded by admitting the 

 instinctive actions of animals as an unsolved difficulty in 

 the way of Berkeley's theory. When my attention was 

 first directed to the subject, this difficulty appeared to me 

 not a merely residual difficulty, like those planetary per- 

 turbations which the theory of gravitation failed to account 

 for in Newton's time ; it appeared to amount to a refuta- 

 tion of the entire theory. But recent speculations on the 

 nature of instinct and of mind, especially the speculations 



