98 SCIENCE AND METHOD. 



without exception were deformed in accordance with 

 the same laws. When I say all bodies without excep- 

 tion, I include, of course, our own bodies and the rays 

 of light emanating from the different objects. 



If we look at the world in one of those mirrors 

 of complicated form which deform objects in an odd 

 way, the mutual relations of the different parts of the 

 world are not altered ; if, in fact, two real objects 

 touch, their images likewise appear to touch. In truth, 

 when we look in such a mirror we readily perceive the 

 deformation, but it is because the real world exists 

 beside its deformed image. And even if this real 

 world were hidden from us, there is something which 

 cannot be hidden, and that is ourselves. We cannot 

 help seeing, or at least feeling, our body and our 

 members which have not been deformed, and continue 

 to act as measuring instruments. But if we imagine 

 our body itself deformed, and in the same way as if 

 it were seen in the mirror, these measuring instruments 

 will fail us in their turn, and the deformation will 

 no longer be able to be ascertained. 



Imagine, in the same way, two universes which are 

 the image one of the other. With each object P in 

 the universe A, there corresponds, in the universe B, 

 an object P^ which is its image. The co-ordinates 

 of this image P^ are determinate functions of those 

 of the object P ; moreover, these functions may be 

 of any kind whatever — I assume only that they are 

 chosen once for all. Between the position of P and 

 that of P^ there is a constant relation ; it matters little 

 what that relation may be, it is enough that it should 

 be constant. 



Well, these two universes will be indistinguishable. 



