440 ELEMENTARY PHYSIOLOGY 



With the index and the middle fingers in their ordinary 

 position, it is of course impossible that the outer sides 

 of each should touch opposite surfaces of one spheroidal 

 body. If, in the natuial and usual position of the fingers, 

 their outer surfaces simultaneously give us the impression 

 of a spheroid (which itself is a complex judgment), it is 

 in the nature of things that there must be two spheroids. 

 But, when the fingers are ci-ossed over the marble, the 

 outer side of each finger is really in contact with a 

 spheroid ; and the mind, taking no cognizance of the 

 crossing, judges in accordance with its universal experience, 

 that two sphei'oids, and not one give rise to the sensations 

 which are perceived. 



2. Judgments are Delusive, not Sensations. — 

 Phenomena of the kind described in tlie preceding 

 section are not uncommonly called dehisiuns of the senses ; 

 but there is no such thing as a fictitious, or delusive, 

 sensation. A sensation must exist to be a sensation, and 

 if it exists, it is real and not delusive. But the judgments 

 we form respecting the causes and conditions of the 

 sensations of which we are aware, ai-e very often erroneous 

 and delusive enough ; and such judgments may be 

 brought about in the domain of every sense, either by 

 artificial combinations of sensations, or by the influence 

 of unusual conditions of the body itself. The latter give 

 rise to what are called subjective setisutio7is. 



Mankind would be sul)ject to fewer delusions than they 

 are, if they constantly bore in mind their liability to false 

 judgments due to unusual combinations, either artificial 

 or natural, of true sensations. Men say, "Ifelt," "I 

 heard," "I saw" such and .such a thing, when, in ninety- 

 nine cases out of a hundred, what they really mean is, 

 that they judge that certain .sensations of touch, liearing, 

 or sight, of which they were conscious, were caused by 

 such and such things. 



3. Subjective Sensations. — Among subjective sensations 

 within the domain of touch, are the feelings of creeping 



