THE MEANING OF PERCEPTION 185 



occurred, as the luminous trail of the meteorite fades when its 

 combustible matter has been consumed. It persists in memory, 

 and it crops out again and again in our consciousness, obtruding 

 itself, as Bergson says, even when we would like to forget it. 

 Something, then, comes into existence as the consequence of 

 sensori-motor activity, and we cannot prove that this is a 

 potential energy stored in the brain, for the latter does not 

 appear to be different when memories coexist with it and when 

 they do not; besides, we can account for all the energy of a 

 sensational process in other ways that are more consonant with 

 scientific methods. And this something continues to exist, and 

 it is utilised (as experience) in future actions, and yet it is not 

 wasted (so, again, it is not energy). And it is real, because it 

 does not fool us (as does a spook), but leads us back to results 

 that are useful and can be verified. What, then, is it, since, 

 apparently, it is not energy ? 



One can only say that it is memory, or " spirit," as Bergson 

 calls it the name does not matter so long as we do not associate 

 with it the (necessarily) non-scientific ideas that are connoted by 

 the term " soul." It is something that belongs (as Bertrand 

 Russell says) to the " ultimate furniture of the world " that is, 

 it is indefinable, just as energy itself cannot be defined in terms 

 of anything else. It may not be a concept peculiar to biology, 

 as we shall try to show later on, but in the meantime we may 

 conveniently regard it as such. Physiology is not concerned 

 with it, and investigates only the chemical and physical processes 

 in which mind or spirit becomes materialised; and psychology, 

 disregarding the concept of energy, starts with that of mind and 

 proceeds with its analysis. 



The *' Categories of the Understanding." 



There are, therefore, both body and mind, or " matter " and 

 " spirit." We shall not argue that this means that there is a 

 dualism, believing with Bergson that matter and spirit are only 

 tendencies that are contrasted in some way or other, or opposite 

 directions, perhaps, of the same series of changes. Assuming, 

 then, the existence of mind as something apart from the organic 

 activities in which it is expressed, we may regard it as legitimate 

 to investigate its working, while disregarding the " link with 

 body." At any rate, it is " up to " science to take that road 

 provisionally and to see to where it leads. 



