IDENTICAL CHANGES 



which cannot be projected through the rock salt. 



Again, in the production of colors, both by re- 

 flection and through means of peculiar transpar- 

 ent bodies, there is an almost infinite individuality. 



And, while the analyzation of the manifold 

 changes wrought by light are probably too subtle 

 for the complete understanding of any one, yet it 

 is certain that these changes are not produced 

 merely by a variation in rapidity of light-waves. 

 For, in the transmission of force from one body to 

 another body, every intervening body must under- 

 go a change. (Proposition XI, B. 1.) And when 

 we put a pane of glass between us and the Sun, 

 that glass does certainly intervene, even as the at- 

 mosphere does. And atmosphere and glass are both 

 changed, in a different degree, by the transmis- 

 sion of the light. But not in degree only does the 

 change produced on the atmosphere differ from the 

 change produced in glass, or in Iceland spar or 

 mica. 



For, in a solid, the interstices cannot continue 

 in straight lines, and the change that a transparent 

 solid undergoes in transmitted light is not a mere 

 negative sifting through the holes, but must needs 

 be connected with the life process of the transparent 

 body. That the accumulated data of the actions 

 of light can be resting on a wrong basis, seems 

 almost incredible, and yet are the ether waves of 

 the dynamic theories an utter impossibility. 



Humans are ever ready to throw aside logical 

 conclusions for popular appearance, and spectral 

 209 



