WHAT IS INTELLIGENCE? 185 



leave it at certain levels all the way down. The ingoing 

 nerve and the outgoing nerve are anatomically and 

 functionally linked in the interior of the cord ; this place 

 is called centre. A centre on its structural side consists 

 of at least one cell on or over which the ending of a nerve 

 fibre is distributed ; usually, of course, many cells go to 

 make up a single centre." 



Then he makes the following statement: "But what, 

 in a few words, is the nervous system for? It is first of 

 all for carrying out certain activities, such as breathing, 

 on a sub-conscious plane, over which the constant super- 

 vision of consciousness would be tedious, if it were not 

 impossible, considering the enormous number of demands 

 made on the attention of the individual. It is in the next 

 place for carrying out certain activities with the greatest 

 possible speed compatible with the greatest possible ac- 

 curacy ; it is for linking up functionally the outer world 

 with our living bodies, allowing it to act on our bodies 

 within certain limits, and reversely acting itself on the 

 outer world, when and to what extent may be found nec- 

 essary. It is for maintaining our posture in stable equili- 

 brium, whether we are sitting, standing or walking, much 

 of this it also does on the sub-conscious plane, the cere- 

 bellum being the great central organ for attending to this 

 important but not necessarily always conscious affair. 



"The element of speed is a very obvious one in the ac- 

 tivities of the nerves ; it is of supreme moment that you 

 drop the red-hot coal as soon as you possibly can, that you 

 wink away the grit in the eye almost the instant it alights. 

 It is of great importance to the artilleryman to fire off his 

 gun the instant he gets the order from the officer to do so, 

 a fraction of a second's delay may mean that he misses the 

 target. It is because the nervous system of the active 

 young man works promptly that he skips out of the way 

 of the motor car, whereas the old gentleman with his 



