THE LIGHT 95 



perceive ? " He perceived ; but the truth 

 had never before occurred to him. 



It is only, however, a part of the truth 

 which those two incidents revealed. The 

 question to be considered is much less 

 how the phenomena of light impress the 

 angler than how they impress the fish. 



From the nature of things, a complete 

 solution of this problem is impossible. 

 Even if we could lie under the water and 

 look upwards, we could have no assurance 

 that our vision of things would be identical 

 with that of a trout. The trout would 

 detect objects that escaped us, and those 

 which were visible to both would be seen 

 differently. The trout could tell a dun- 

 winged fly with a claret body from a dun- 

 winged fly with a red body ; but to the 

 human eye the flies would be very much 

 alike from three feet under the surface. 



Still, there is a respect in which, 

 looking upwards into the air, the trout 

 and the human observer would be at one ; 

 and this unity is of great importance in 

 relation to the general assumption that 



