STRUCTURE OF SENSIFEROUS ORGANS 309 



more or less convenient working hypothesis. But, 

 if I must choose among them, I take the " law of 

 parcimony " for my guide, and select the simplest 

 namely, that the sensation is the direct effect of 

 the mode of motion of the sensorium. It may 

 justly be said that this is not the slightest ex- 

 planation of sensation; but then am I really any 

 the wiser, if I say that a sensation is an activity 

 (of which I know nothing) of a substance of mind 

 (of which also I know nothing) ? Or, if I say that 

 the Deity causes the sensation to arise in my mind 

 immediately after he has caused the particles of 

 the sensorium to move in a certain way, is any- 

 thing gained? In truth, a sensation, as we have 

 already seen, is an intuition a part of immediate 

 knowledge. As such, it is an ultimate fact and 

 inexplicable; and all that we can hope to find out 

 about it, and that indeed is worth finding out, is 

 its relation to other natural facts. That relation 

 appears to me to be sufficiently expressed, for all 

 practical purposes, by saying that sensation is the 

 invariable consequent of certain changes in the 

 sensorium or, in other words, that, so far as we 

 know the change in the sensorium is the cause of 

 the sensation. 



I permit myself to imagine that the untutored, 

 if noble, savage of " common sense " who has been 

 misled into reading thus far, by the hope of get- 

 ting positive solid information about sensation, 

 giving way to not unnatural irritation, may here 



