88 VISION. 



universe ? Is it philosophical to suppose that there 

 is no other universe than that which is indicated to 

 us by whirling spheres that roll through space, 

 and that these must be shorn even of those pro- 

 perties by which they directly affect our senses, 

 the properties by which alone we have acquired 

 knowledge of their existence ? It is easy to see 

 what strange possibilities may be opened up by 

 such a question, but that is no reason why the 

 question should not be asked. Either we must 

 suppose that the sensations of sight and sound 

 have links in some way corresponding to them in 

 a world of which we know nothing, or that they 

 are arbitrary illusions, graduated doubtless in keep- 

 ing with movements not directly appreciable by us, 

 but arbitrary nevertheless. 



