. 



AND THE MICROSCOPE. 17 



What is the world wherein the eye finds its home 

 what the domain of sight ? The world of light and colour. 

 The light 



" From matter streaming, it makes matter bright, 

 Matter arrests it on its onward flight 

 And so I fancy 'twill but have its day, 

 And when the matter vanishes, so fade away." 



In a few powerful touches, Mephistopheles thus reviews the 

 whole doctrine of light. Light, if we contemplate it wholly 

 by itself, is not transparent, not yellow and blue and red ; 

 light is a motion of a matter of extreme tenuity extending 

 through all space, the ether vibrations which are propa- 

 gated in straight lines through this, like the waves of 

 sound through the air. In their straight course they strike 

 upon bodies which lie in their way and if the body is what 

 we call opaque, recoil like billows striking on the sea-shore ; 

 but if the body is transparent, they pass through like 

 waves through a canal opening into the sea. Coal-gas 

 burns, and during its combination with oxygen, it sets the 

 ether vibrating, it emits light ; the coal-gas is burnt, and 

 with the matter which has " vanished," " faded " the light. 

 An infinite ocean of ether filling the whole universe, and 

 in it thousands upon thousands of waves hastening in 

 every possible direction, crossing, destroying or deadening 

 each other ; this is the material nature of light and colour. 

 Who can say that he has seen this light, these colours ? 

 So little are we in a condition to do it, that the acuteness 

 of the greatest intellects was required to unfold to us this 

 the true nature of light. 



Through the thick roof of vine-leaves, a sunbeam trem- 

 bles in the calm, favouring shade ; you believe it is the ray 

 of light you see ; but far from that, what you perceive is 



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