100 SCIENCE AND METHOD. 



One part of space is not by itself and in the absolute 

 sense of the word equal to another part of space, for 

 if it is so for us, it will not be so for the inhabitants of 

 the universe B, and they have precisely as much right 

 to reject our opinion as we have to condemn theirs. 

 • I have shown elsewhere what are the consequences 

 of these facts from the point of view of the idea that 

 we should construct non-Euclidian and other analogous 

 geometries. I do not wish to return to this, and 

 I will take a somewhat different point of view. 



II. 



If this intuition of distance, of direction, of the 

 straight line, if, in a word, this direct intuition of space 

 does not exist, whence comes it that we imagine 

 we have it? If this is only an illusion, whence comes 

 it that the illusion is so tenacious? This is what 

 we must examine. There is no direct intuition of 

 magnitude, as we have said, and we can only arrive 

 at the relation of the magnitude to our measuring 

 instruments. Accordingly we could not have con- 

 structed space if we had not had an instrument 

 for measuring it. Well, that instrument to which we 

 refer everything, which we use instinctively, is our 

 own body. It is in reference to our own body that we 

 locate exterior objects, and the only special relations 

 of these objects that we can picture to ourselves are 

 their relations with our body. It is our body that 

 serves us, so to speak, as a system of axes of 

 co-ordinates. 



For instance, at a moment a the presence of an 

 object A is revealed to me by the sense of sight ; at 

 another moment /i the presence of another object 



