260 SENSATION AND THE SENSIFEROUS ORGANS. [LECT. 



the sense organ. The sense organ, again, is only a 

 mediate cause by reason of its producing a molecular 

 change in the nerve fibre ; while this last change is 

 also only a mediate cause of sensation, depending, as 

 it does, upon the change which it excites in the 

 sensorium. 



The sense organ, the nerve, and the sensorium, 

 taken together, constitute the sensiferous apparatus. 

 They make up the thickness of the wall between the 

 mind, as represented by the sensation "muskiness," 

 and the object, as represented by the particle of musk 

 in contact with the olfactory epithelium. 



It will be observed that the sensiferous wall and 

 the external world are of the same nature ; whatever 

 it is that constitutes them both is expressible in terms 

 of matter and motion. Whatever changes take place 

 in the sensiferous apparatus are continuous with, and 

 similar to, those which take place in the external 

 world. 1 But, with the sensorium, matter and motion 



1 The following diagrammatic scheme may help to elucidate the 

 theory of sensation : 



Mediate Knowledge 



Physical World 



Mental World 



Not Self 



Self 



Non-Ego or Object Ego or Subject 



Immediate knowledge is confined to states of consciousness, or, in other 



