THE ANALYSIS OF BEHAVIOUR 133 



organ, where it is all expended on releasing the potential energy 

 which is to produce the effect in question. Or suppose (for it 

 does not matter to our argument in the least) that some of the 

 energy entering the sensori-motor system is dissipated, or wasted, 

 or " lost " by " friction " (as some would actually be " lost " in 

 the billiard-ball model). This dissipated energy will therefore 

 appear in the form of heat, and the rest will be transmitted as 

 before to the effector organ. Where, then, does the conscious- 

 ness of having seen something and acted upon the stimulus so 

 received come from ? For we must consider the suggestion that 

 an affection of consciousness is the result of an energy trans- 

 formation ; that it comes from the energy of light that stimulated 

 the retina and transformed into a nervous impulse just in the 

 same way as the heating of a metallic filament is the result of the 

 transformation of an electric current which passes through a lamp. 

 We are not going to accept this suggestion, but we notice it 

 in order that the reader may see quite clearly what are the 

 various possibilities (let us say) : 



(1) All the energy that comes from without the body and 

 stimulates a sense organ is transmitted without loss through the 

 peripheral and central nervous system, and is physically trans- 

 formed in the effector organ, releasing potential energy there 

 which does work. 



(2) Some of it is dissipated, and the rest is transmitted as above. 



(3) Some of it is transmitted as in (1), with or without dissipa- 

 tion, and some of it is physically transformed into " consciousness." 



Now what we know suggests that there is extremely little 

 or even no dissipation of energy in the transmission of a nervous 

 impulse through a reflex arc. And the more we think about the 

 third of our three hypotheses, the more unlikely it appears to be. 

 At all events, it does not seem possible even to attempt to verify it. 



We return to this discussion in a later chapter. Meanwhile, 

 let the reader note that all that we have studied so far all, indeed, 

 that it appears that cerebral physiology can study are the ways 

 in which the stimulation of the organs of sense set up nervous 

 impulses, the paths along which those impulses travel in the 

 central nervous system, and the motor and secretory effects that 

 they produce. There is nothing at all about a theory of know- 

 ledge in the results of such an investigation, but very much 

 about a theory of action. Sensation is not something that 

 enables us to contemplate the external world, but is rather that 



