THE RELATIVITY OF SPACE. loi 



B is revealed by another sense, that, for instance, 

 of hearing or of touch. I judge that this object B 

 occupies the same place as the object A. What does 

 this mean ? To begin with, it does not imply that 

 these two objects occupy, at two different moments, 

 the same point in an absolute space, which, even 

 if it existed, would escape our knowledge, since 

 between the moments a and fi the solar system has 

 been displaced and we cannot know what this dis- 

 placement is. It means that these two objects occupy 

 the same relative position in reference to our body. 



But what is meant even by this } The impressions 

 that have come to us from these objects have followed 

 absolutely different paths — the optic nerve for the 

 object A, and the acoustic nerve for the object B ; 

 they have nothing in common from the qualitative 

 point of view. The representations we can form of 

 these two objects are absolutely heterogeneous and 

 irreducible one to the other. Only I know that, 

 in order to reach the object A, I have only to extend 

 my right arm in a certain way ; even though I refrain 

 from doing it, I represent to myself the muscular and 

 other analogous sensations which accompany that 

 extension, and that representation is associated with 

 that of the object A. 



Now I know equally that I can reach the object B 

 by extending my right arm in the same way, an 

 extension accompanied by the same train of muscular 

 sensations. And I mean nothing else but this when 

 I say that these two objects occupy the same 

 position. 



I know also that I could have reached the object A 

 by another appropriate movement of the left arm, 



