SENSATION ADD THE SENSIFEROUS ORGANS. 265 



Thus, modern investigation supplies a representative 

 of the Epicurean simulacra in the volatile particles of the 

 musk ; but it also gives us the stamp of the particles on 

 the olfactory epithelium, without any transmission of 

 matter, as the equivalent of the Aristotelian "form;" 

 while, finally, the modes of motion of the molecules of 

 the olfactory cells, of the nerve, and of the cerebral 

 sensorium, which are Hartley's vibrations, may stand 

 very well for a double of the "intentional species" of 

 the Schoolmen. And this last remark is not intended 

 merely to suggest a fanciful parallel ; for, if the cause of 

 the sensation is, as analogy suggests, to be sought in the 

 mode of motion of the object of sense, then it is quite 

 possible that the particular mode of motion of the 

 object is reproduced in the sensorium ; exactly as the 

 diaphragm of a telephone reproduces the mode of motion 

 taken up at its receiving end. In other words, the 

 secondary " intentional species " may be, as the School- 

 men thought the primary one was, the last link between 

 matter and mind. 



None the less, however, does it remain true that no 

 similarity exists, nor indeed is conceivable, between the 

 cause of the sensation and the sensation. Attend as 

 closely to the sensations of muskiness, or any other 

 odour, as we will, no trace of extension, resistance, or 

 motion is discernible in them. They have no attribute 

 in common with those which we ascribe to matter ; they 

 are, in the strictest sense of the words, immaterial entities. 



Thus, the most elementary study of sensation justi- 



