I. 



THE RELATIVITY OF SPACE. 



I. 



It is impossible to picture empty space. All our 

 efforts to imagine pure space from which the changing 

 images of material objects are excluded can only 

 result in a representation in which highly-coloured 

 surfaces, for instance, are replaced by lines of slight 

 colouration, and if we continued in this direction to the 

 end, everything would disappear and end in nothing. 

 Hence arises the irreducible relativity of space. 



Whoever speaks of absolute space uses a word de- 

 void of meaning. This is a truth that has been long 

 proclaimed by all who have reflected on the question, 

 but one which we are too often inclined to forget. 



If I am at a definite point in Paris, at the Place 

 du Pantheon, for instance, and I say, " I will come 

 back here to-morrow ; " if I am asked, " Do you mean 

 that you will come back to the same point in space.?" 

 I should be tempted to answer yes. Yet I should 

 be wrong, since between now and to-morrow the earth 

 will have moved, carrying with it the Place du Pan- 

 thdon, which will have travelled more than a million 

 miles. And if I wished to speak more accurately, I 

 should gain nothing, since this million of miles has 



