KNOWLEDGE AND BELIEF. 305 



regard to the lower senses — taste, sex-sense, touch, 

 and temperature — man has by no means reached the 

 highest stage in every respect. 



We can naturally only pass judgment on the 

 sensations which we ourselves experience. However, 

 anatomy informs us of the presence in the bodies of 

 many animals of other senses than those we are 

 familiar with. Thus fishes and other lower aquatic 

 vertebrates have peculiar sensilla in the skin which 

 are in connection with special sense-nerves. On the 

 right and left sides of the fish's body there is a long 

 canal, branching into a number of smaller canals at 

 the head. In this " mucous canal " there are nerves 

 with numerous branches, the terminations of which 

 are connected with peculiar nerve-aggregates. This 

 extensive epidermic sense-organ probably serves for 

 the perception of changes in the pressure, or in other 

 properties, of the water. Some groups are distin- 

 guished by the possession of other peculiar sensilla, 

 the meaning of which is still unknown to us. 



But it is already clear from the above facts that 

 our human sense-activity is limited, not only in 

 quantity, but in quality also. We can thus only 

 perceive with our senses, especially with the eye and 

 the sense of touch, a part of the qualities of the 

 objects in our environment. And even this partial 

 perception is incomplete, in the sense that our organs 

 are imperfect, and our sensory nerves, acting as inter- 

 preters, communicate to the brain only a translation 

 of the impressions received. 



However, this acknowledged imperfection of our 

 senses should not prevent us from recognizing their 

 instruments, and especially the eye, to be organs of 

 the highest type ; together with the thought-organs in 



