Does Matter Exist? 



by its vibrations the radiations of light, heat, 

 electricity, and perhaps even actions at a distance, 

 such as the attraction exercised between heavenly 

 bodies. 



I am well aware that at the mention of ether 

 those who are not in constant contact with 

 scientific thought cannot avoid feeling incredu- 

 lous. They find it difficult to accept the reality 

 of such a medium, which our senses cannot reach 

 directly, and wonder whether we are not allow- 

 ing ourselves to be deceived by philosophical 

 dreaming. On the other hand scientists have, 

 by force of habit, come to believe in ether as we 

 believe in our own existence. This deep faith 

 does not prove them to be in the right, but the 

 disagreement vanishes when we take the trouble 

 to clearly understand the value and the implica- 

 tions of our scientific hypotheses. It must be 

 clearly understood that we pretend to no know- 

 ledge concerning the reality of the external 

 world. We know only our own sensations, due 

 either to observation or to experiment ; all we 

 attempt is therefore to form a mental image in 

 agreement with these sensations; our preten- 

 sions go no further. We are like people looking 



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