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as abstract symbols. Professor Lorentz is quite ex- 

 plicit on this point, as he holds that, " while thus deny- 

 ing the real existence of ether stresses, we can still 

 avail ourselves of all the mathematical transformations 

 by which the application of the formula (for these 

 stresses) may be made easier: . . . and for conveni- 

 ence's sake we may continue to apply to the quantities 

 occurring in this integral the name of stresses. Only, 

 we must be aware that they are only imaginary ones, 

 nothing else than auxiliary mathematical quantities." 

 This dematerialization of the ether, when it was once 

 found that light and heat still managed to come to us 

 from the sun although we had given its medium of 

 transmission such a rude shock, has progressed rapidly 

 until to-day many accept the postulate that there is no 

 difference between absolutely vacuous space and the 

 ether, except that the latter is the temporary seat of 

 radiant energy and possesses a light vector. If this 

 definition of space means anything, it implies that light 

 has the power of changing a vacuum into a substance. 

 When we stop to think that a vacuum means absolute 

 negation of everything, we realize what an extraordi- 

 nary thing light is in modern physics. Just consider 

 this statement of Professor Einstein, which is con- 

 sidered almost authoritative, " the places in space 

 where these electro-magnetic actions (i.e., light) occur 

 are here considered not as states of a sort of matter, 

 but as self-existing things which are similar to ponder- 



