CHAPTER XVI 



ON" SENSATIONS IN GENERAL 



FIRST SECTION" 



QUALITATIVE RELATIONS BETWEEN STIMULUS 

 AND SENSATION 



WE obtain our knowledge of the outside world entirely through our senses. 

 The sense of touch, taken in its widest acceptation, teaches us to recognize 

 the nature of those objects about us which come into actual contact with our 

 bodies, and gives us information concerning the temperature of these and 

 more distant objects. 



By the sense of taste we can distinguish certain properties of such sub- 

 stances as can be placed in the mouth. 



The sense of smell enables us to judge something of the nature of the 

 atmosphere. For certain animals this sense is of very great importance, in 

 that it furnishes the possessor with knowledge of prey or of enemies even 

 at a considerable distance. 



By the sense of hearing we are made aware of those vibrations of solid, 

 fluid or gaseous bodies, which strike the ear. Through this sense we obtain 

 knowledge not only of what goes on immediately about us, but also of what 

 takes place at a distance. 



The sense of sight reaches out to a still greater distance. By its help 

 we can penetrate to the farthest point from which light rays can reach the eye. 



But our sensations * do not all relate to the outside world. From all the 

 organs of the body information of their condition and of the processes taking 

 place within them is all the time being brought by appropriate nerves to the 

 central nervous system. Some of these messages never rise into consciousness, 

 but have a controlling influence on the functions of the body through the 

 lower nerve centers. Others rise to the plane of consciousness and eventuate 



1 By sensation we mean the simplest possible state of consciousness, one which cannot 

 be analyzed into simpler components. But a sensation corresponding to this definition 

 probably never exists, for psychological analysis has demonstrated that even the simplest 

 conscious processes are really composed of several simple sensations. For example, the 

 simple sensation of sweetness is always associated with the feeling that we have something 

 in the mouth ; the sensation of a color likewise is complicated by its projection to a certain 

 place in the outside world, etc. These processes in consciousness we shall designate as 

 ideas. 



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