PHYSIOLOGICAL PARADOXES. 



of square boards, and when a red patch, con- 

 sisting of nine of these boards, and looking at 

 a distance like a small red spot, was seen to 

 move from one part of the field to another, 

 there was, in fact, no real object which did 

 move across the field. Now, in real life we 

 have not merely surfaces, but substances (with 

 depth as well as length and breadth), to deal 

 with. Is it conceivable that, when the sub- 

 stantial objects with which we are acquainted 

 appear to move from place to place, this appear- 

 ance is due not to the movement of any sub- 

 stantial object, but to the cessation in one 

 place of arrangements which produced the 

 phenomena of that object and the production 

 of those arrangements in fresh positions, so as 

 to give the appearance of movement of the 

 object ? This would be parallel, in our field 

 of boards, to the cessation in one place of the 

 arrangement of boards with red sides up and 

 the production of this arrangement in other 

 positions. 



Such a scheme is not only conceivable. 

 It is as much in accordance with the facts of 

 observation as any other scheme of matter and 

 motion, while better able, as we have seen, to 

 explain such facts as the swifter passing the 

 slower. 



There is already good reason to believe 

 that all matter would prove, on its ultimate 

 analysis, to be material of one kind, and that 



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