AS THE BIOLOGIST SEES IT 



non-existent. Color is color to us and 

 sound sound only after a mental percep- 

 tion. But the different ether waves which 

 are perceived by us as color and the 

 atmospheric waves as sound might per- 

 fectly imaginably go on coursing through 

 the ether and atmosphere although no 

 human or animal sense-organs and brains 

 perceived them. In fact the physicist 

 is quite sure they would. If a photo- 

 graphic plate got in the way of the light 

 waves and a phonographic plate in the 

 way of the sound waves the existence of 

 these waves would be mechanically reg- 

 istered. 



In Stanford University a number of 

 years ago I used to walk down an avenue 

 lined with trees I believe they were 

 trees to the beautiful quadrangle of 

 buildings, with a companion, now a 

 distinguished professor of philosophy in 

 an important Eastern university, who 

 proved during our walk each morning 

 by what was to me a verbally irrefutable 

 logical argument that there were no trees 



