The Senses 207 
The Sense of Sight 
Birds, so wonderful and interesting in all their structure 
and life, have that most treasured of all the senses— 
sight—so highly developed that there is nothing with 
which we can compare it among living creatures. With 
our great telescopes we can see to a greater distance than 
any bird; with the high-power lenses of our microscopes 
we can distinguish infinitely smaller objects than any 
feathered creature is capable of perceiving, but where 
else on the earth is there an organ of vision which in a 
fraction of time can change itself from telescope to micro- 
scope; where is the eye that, seeing with wonderful clear- 
ness in the atmosphere, suddenly adapts itself to the re- 
fraction of water, or (less slowly, although no less surely) 
to the darkness of night? 
Next to our powers of reasoning, we value sight above 
all things, and fortunate indeed should we be could we 
but exchange our imperfect vision for sight like that of 
an eagle! Little need of spectacles or binoculars has he, 
for the perfection of his eye enables him to become near- 
sighted or far-sighted at will. 
“The eye,’”’ says Professor Coues, ‘is an exquisitely 
perfect optical instrument, like an automatic camera 
which adjusts its own focus, photographs a picture upon 
its sensitized retinal plate, and telegraphs the molecu- 
lar movements of the nervous sheet to the optic ‘twins’ 
of the brain, where the result is translated from the phys- 
ical terms of motion in matter to the mental terms of 
consciousness. But no part of the nervous tract, from 
