318 THE BODY AT WORK 



e very-moment impulses from the nose, carried by the fifth 

 nerve to this region, ought not to appear in consciousness at 

 all ; but owing to the excited condition in which they find the 

 grey matter they assume an importance which does not belong 

 to them, and discharge the reflex action of sneezing, just as 

 they would do had one taken snuff. Several lessons are to be 

 learned from this phenomenon as, for example, one which 

 cannot be too often impressed, that the impulses which appear 

 in consciousness (or, more accurately, the impulses to which 

 attention is directed) are but a most insignificant fraction of 

 those delivered by sense-organs to the central nervous system. 

 The impulses which give rise to the sensation of tickling in 

 the nose are not exceptional impulses which happened to be 

 started when the light fell on the eye. They were reaching the 

 brain in a steady flow before the agitation of the mid-brain 

 gave to them exceptional force. No consideration regarding 

 the working of the nervous system has a more important 

 bearing than this. We cannot picture to ourselves the activity 

 of the sensory nervous system. Our experience is limited to 

 the scattered sensations which we perceive. Are the sensory 

 nerve-endings incessantly responding to external forces, 

 throwing an almost continuous procession of impulses up 

 each of the millions of nerve-fibres which connect them 

 with the central system ? Such a conception is probably 

 nearer to the truth than the conception which we should 

 develop if we trusted to experience. Yet even experience 

 tells us that an infinity of messages is delivered to the brain, 

 of which consciousness takes no account. Changing trains 

 at a roadside station in France, my attention was attracted 

 by an electric bell on the platform, which was ringing con- 

 tinuously. " Why does the bell ring ?" I asked the station- 

 master. " To make known that everything goes well," was 

 the response. "If it stops, something is wrong." " But do 

 you not become so accustomed to it that you cease to hear it ?" 

 " Yes, truly ; it rings day and night. One does not pay atten- 

 tion to it until it has stopped." Sensory impulses generated by 

 the contact of my skin with the chair that I am sitting on are 

 incessantly ringing the bell of consciousness. I should notice 

 them immediately if they stopped. As it is, they do not attract 

 my attention until they ring a little louder than usual, or until 



