THE MEANING OF PERCEPTION 183 



One must think of tlie brain of a higher animal as the junction 

 of nervous paths which are extraordinarily numerous. All 

 evolution of the central nervous system increases the number of 

 alternative paths which a stimulus entering the brain may take, 

 so that any receptor organ anywhere in the body, may be re- 

 garded as capable of giving rise to a nervous impulse that may 

 enter the brain and become shunted on to the paths leading to any 

 other part of the body. Lay down some " beaten track " in this 

 labyrinth, and we establish a motor habit and so create experience. 

 And what is common to all automatic activity, whether it be 

 that of a heliotropic insect larva, an instinctively acting bird or 

 mammal, or a trained worker of any kind, is the existence of 

 experience, which is expressed by these ready-made motor 

 mechanisms. But the responses of the heliotropic and instinctive 

 animals are the results of inherited motor habits, whereas the 

 skilled worker has to make them for himself, and he does not 

 transmit them by heredity. 



Quite plainly, pure memory is something different from this 

 motor habit experience. The latter is the persistence of the 

 mechanism of receptors, nervous tracts, and muscles that were 

 affected in the formation of an action of some kind, but pure 

 memory we must regard as the persistence of the perceptions that 

 accom'panied the action when it was being learned. It becomes 

 manifest, apart from the motor habit (which is manifested in 

 action) in pure recollection, in reverie, in dreams, or in the power 

 of visualisation that most people have in some degree. We must 

 think of all the perceptions that we have ever had as continuing 

 to exist somehow, mingled together to form a " multiplicity in 

 unity " — that is, as something which is manifold in its nature, 

 but which is not spread out, as it were, in space. The elements 

 (or constituent notes) of a musical arpeggio are heard, one after 

 another, and so are separate from each other in time ; but the 

 same notes, played together perfectly, are heard by a musician 

 and recognised as individual, although they blend to form a mani- 

 fold or a multiplicity in unity. Memory, then, is something 

 analogous, the fusion, as it were, in one of all our past perceptions. 

 Where is it, and how is it stored ? Undoubtedly it hangs 

 together in some way with the cerebral substance, and the older 

 hypotheses stated that memories were stored away in the cells 

 of the grey matter of the brain, and could be extirpated by the 

 removal of the latter structures. Now, although few biologists 



