THE VITAL IMPETUS 157 



Physiology shows us as clearly as possible that in the 

 stimulation of a receptor organ, the propagation of a 

 nervous impulse along an afferent nerve, the trans- 

 mission of this impulse through the cord or brain, or 

 both in the propagation again of the impulse through 

 an efferent nerve and the transformation of this 

 impulse into a releasing agency, setting free the energy 

 potential in the muscle substance that in all this 

 there can be nothing more than physico-chemical 

 energy-transformations. All this is clear and certain. 

 But why should the same afferent stimuli, entering 

 the central nervous system at different times by the 

 same avenues, and in the same manner, traverse 

 different tracts, and issue along different efferent 

 nerves, producing different results ? Or why should 

 different stimuli entering the central nervous system 

 take the same intra-cerebral paths and then affect the 

 same efferent nerves and effector organs ? It is 

 because these stimuli lead to perceptions which fuse 

 with, and become part of the duration of, the organism. 

 And the response then becomes a response not to 

 the physical stimulus, but to the duration modified in 

 this way. 



Can we conceive of any physical mechanism in 

 which the duration of the organism accumulates ? 

 Can we think of any way in which memories are 

 stored in the central nervous system ? When we say 

 ' stored," it is our ingrained habit of thinking in terms 

 of space and number that makes us regard memories 

 as laid by somewhere, in the way we file papers in a 

 cabinet, or store specimens in a museum. Supposing 

 perceptions are stored in this way, we think of them 

 as stored or recorded in the same way as a conversa- 

 tion is recorded and stored in a phonograph. The 

 phonograph can reproduce the conversation just as 



