656 SCIENCE AND HYPOTHESIS 



world would no doubt attribute four dimensions to complete visual 

 space. 



Tactile and Motor Space. " Tactile space " is more complicated 

 still than visual space, and differs even more widely from geometrical 

 space. It is useless to repeat for the sense of touch my remarks 

 on the sense of sight. But outside the data of sight and touch there 

 are other sensations which contribute as much and more than they do 

 to the genesis of the concept of space. They are those which every- 

 body knows, which accompany all our movements, and which we usu- 

 ally call muscular sensations. The corresponding framework con- 

 stitutes what may be called motor space. Each muscle gives rise to a 

 special sensation which may be increased or diminished so that the 

 aggregate of our muscular sensations will depend upon as many 

 variables as we have muscles. From this point of view motor space 

 would have as many dimensions as we have muscles. I know that it is 

 said that if the muscular sensations contribute to form the concept 

 of space, it is because we have the sense of the direction of each move- 

 ment, and that this is an integral part of the sensation. If this were 

 so, and if a muscular sense could not be aroused unless it were accom- 

 panied by this geometrical sense of direction, geometrical space would 

 certainly be a form imposed upon our sensitiveness. But I do not see 

 this at all when I analyze my sensations. What I do see is that the 

 sensations which correspond to movements in the same direction are 

 connected in my mind by a simple association of ideas. It is to this 

 association that what we call the sense of direction is reduced. We 

 cannot therefore discover this sense in a single sensation. This asso- 

 ciation is extremely complex, for the contraction of the same muscle 

 may correspond, according to the position of the limbs, to very differ- 

 ent movements of direction. Moreover, it is evidently acquired; it is 

 like all associations of ideas, the result of a habit. This habit itself 

 is the result of a very large number of experiments, and no doubt if 

 the education of our senses had taken place in a different medium, 

 where we would have been subjected to different impressions, then 

 contrary habits would have been acquired, and our muscular sensations 

 would have been associated according to other laws. 



Characteristics of Representative Space. Thus representative 

 space in its triple form visual, tactile, and motor differs essen- 

 tially from geometrical space. It is neither homogeneous nor iso- 

 tropic ; we cannot even say that it is of three dimensions. It is often 

 said that we " project " into geometrical space the objects of our 

 external perception ; that we " localize " them. Now, has that any 

 meaning, and if so what is that meaning? Does it mean that we 

 represent to ourselves external objects in geometrical space ? Our rep- 

 resentations are only the reproduction of our sensations; they cannot 

 therefore be arranged in the same framework that is to say, in 



