THE CAUSATION' OF DISEASE. 



67 



to the cortical centres, and thus striking, as it were, a volu- 

 minous chord of feeling (see Fig. 4). It is this which gives 



Fig. 4. 



V Cortical sensory 

 \^ centres, ana- 

 logous to the 

 organ pipes. 



- Peripheral expansions of the 

 sensory nerves, analogous 

 to the keyboard of the 

 organ. 



Diagram showing the different sensory system. To the right are 

 the intellectual senses in the order of their intellectual value. 

 These all give information of the outer world. The muscular 

 sense occupies a peculiar and independent position. To the left 

 are the organic sense-systems. 



rise to the sense of existence — to the feeling " I am" The 

 sensations of sight and hearing, and, in a lesser degree, of 

 taste, are essentially the intellectual sensations, those, namely, 

 which give us accurate information of the world without, which 

 we can remember best, and between minute differences in which 

 we can discriminate most accurately. The organic sensations of 

 the muscles,* viscera, and, to a large degree, of touch, are more 

 voluminous ; our memory of them is also less ; we have, further, 

 only a small power of discriminating between minute shades of 

 difference in these sensations, and (excepting touch sensations) 

 they give us no information concerning the outer world. It is 

 on these voluminous and n on- intellectual sensations that the 

 emotions are grounded. The accompanying diagrams are in- 

 tended to show the mode in which sensations are produced. 



* These must be carefully distinguished from the " muscular sense " or power 

 of estimating the degree of muscular contraction. This plays a very important 

 part in intellectual processes. 



F 2 



