Continuity 45 



electron, or the vibrations of a pendulum 

 or the waves of light. All these are con- 

 crete and tractable physical entities; but 

 space and time are ultimate data, ab- 

 stractions based on experience. We know 

 them through motion, and through 

 motion only, and motion is essentially 

 continuous. We ought clearly to dis- 

 criminate between things themselves and 

 our mode of measuring them. Our 

 measures and perceptions may be af- 

 fected by all manner of incidental and 

 trivial causes, and we may get confused 

 or hampered by our own movement; 

 but there need be no such complication 

 in things themselves, any more than a 

 landscape is distorted by looking at it 

 through an irregular window-pane or 

 from a travelling coach. It is an ancient 

 and discarded fable that complications 

 introduced by the motion of an observer 

 are real complications belonging to the 

 outer universe. 



Very well, then, what about the Ether; 

 is that in the same predicament? Is that 

 an abstraction, or a mere convention, or 



