126 HUME v 



In short, it seems hard to assign any good 

 reason for denying to the higher animals any men- 

 tal state, or process, in which the employment 

 of the vocal or visual symbols of which language 

 is composed is not involved; and comparative 

 psychology confirms the position in relation to 

 the rest of the animal world assigned to man by 

 comparative anatomy. As comparative anatomy 

 is easily able to show that, physically, man is but 

 the last term of a long series of forms, which lead, 

 by slow gradations, from the highest mammal to 

 the almost formless speck of living protoplasm, 

 which lies on the shadowy boundary between 

 animal and vegetable life; so, comparative psy- 

 chology, though but a young science, and far 

 short of her elder sister's growth, points to the 

 same conclusion. 



In the absence of a distinct nervous system, 

 we have no right to look for its product, conscious- 

 ness: and, even in those forms of animal life in 

 which the nervous apparatus has reached no 

 higher degree of development, than that exhibited 

 by the system of the spinal cord and the foun- 

 dation of the brain in ourselves, the argument 

 from analogy leaves the assumption of the exist- 

 ence of any form of consciousness unsupported. 

 With the super-addition of a nervous apparatus 

 corresponding with the cerebrum in ourselves, it 

 is allowable to suppose the appearance of the 

 simplest states of consciousness, or the sensations; 



