46 ORGANIC EVOLUTION CONSIDERED 



substance can exist all around and in us which we 

 cannot detect with any of our senses, or shall we 

 believe that energy can pass through a vacuum? We 

 know that matter may exist in such conditions that ife 

 does not appeal to our senses. When the atmosphere 

 in which we live is perfectly quiet it excites no one of 

 our senses, and we are unconscious of its existence. 

 If this is true of matter so dense as our air, it can 

 easily be imagined that a substance might exist so 

 attenuated as to escape our senses. We cannot weigh 

 ether, because we cannot exhaust it from a vessel, 

 owing to the fact that it passes readily through the 

 densest solids ; nor can we, for the same reason, con- 

 dense it. 



It may be said, however, that ether in motion as 

 light, heat and electricity, appeals to the senses. 



We must, in fact, believe in the existence of ether 

 unless we choose to fall back upon the corpuscular 

 theory of radiant energy — a theory which totally fails 

 to explain many of the phenomena of light. 



We conclude, therefore, that all space in the uni- 

 verse is filled with matter and ether, every atom of 

 which is in constant agitation ; that each can receive 

 motion from, and impart motion to, the other, and 

 that by means of ether as a medium, the radiant 

 energy of the universe may be distributed through 

 space with the velocity of light. According to this 

 view all physical energy is held by matter and ether. 



Matter is continually imparting its radiant energy 

 to ether. Must not the time finally come when all 

 the energy of matter which can be radiated will be 

 imparted to ether and dissipated through infinite 

 space? The quantity of matter in the universe is 

 finite, and consequently the quantity of energy in this 

 matter is finite. It cannot, therefore, require infinite 

 time in which to part with its radiant energy. Owing 



