m.] THE MEANING OF EVOLUTION 263 



what there is of nascent action in the corresponding 

 psychical state, that the psychical state tells us more 

 than the cerebral state. The consciousness of a living 

 being, as we have tried to prove elsewhere, is inseparable 

 from its brain in the sense in which a sharp knife is in- 

 separable from its edge: the brain is the sharp edge by 

 which consciousness cuts into the compact tissue of events, 

 but the brain is no more coextensive with consciousness 

 than the edge is with the knife. Thus, from the fact that 

 two brains, like that of the ape and that of the man, are 

 very much alike, we cannot conclude that the correspond- 

 ing consciousnesses are comparable or commensurable. 



But the two brains may perhaps be less alike than 

 we suppose. How can we help being struck by the fact 

 that, while man is capable of learning any sort of exer- 

 cise, of constructing any sort of object, in short of ac- 

 quiring any kind of motor habit whatsoever, the faculty 

 of combining new movements is strictly limited in the 

 best-endowed animal, even in the ape? The cerebral 

 characteristic of man is there. The human brain is 

 made, like every brain, to set up motor mechanisms 

 and to enable us to choose among them, at any instant, 

 the one we shall put in motion by the pull of a trigger. 

 But it differs from other brains in this, that the number 

 of mechanisms it can set up, and consequently the choice 

 that it gives as to which among them shall be released, 

 is unlimited. Now, from the limited to the unlimited 

 there is all the distance between the closed and the open. 

 It is not a difference of degree, but of kind. 



Radical therefore, also, is the difference between ani- 

 mal consciousness, even the most intelligent, and human 

 consciousness. For consciousness corresponds exactly to 

 the living being's power of choice; it is co-extensive with 

 the fringe of possible action that surrounds the real action: 



