SINGLE VISION. 9 



feeling is not always the predominant, but 

 sometimes the inferior sense ; that its informa- 

 tions are not constant and original, but change- 

 ful and derived ; positions directly contrary to 

 those he had immediately before maintained. 

 But, in the first instance of difference between 

 the informations of the two senses, what rule 

 had we for determining which .was the most 

 worthy of credit ? How does a blind man cor- 

 rect his errors of touch ? If the button be felt 

 double, because pressed by two parts not ac- 

 customed to feel the same thing at the same 

 time, there must have been a period in the life 

 of every person, when a body pressed by any 

 two parts would have been felt double, by three 

 parts triple, and so on. Nor could sight have 

 corrected those deceptions, if they can be called 

 such ; for every thing, by the same hypothesis, 

 must then have also been seen double. How 

 came we, therefore, both to feel and see things 

 single ? Surely not by comparing the informa- 

 tions of the two senses together. 



But, secondly, were we to grant that the 

 sense of touch has originally and constantly 

 informed us that objects are single, it would 

 not follow, that we are thence taught to see 

 them also single. For, since the place which 

 an object seems to either eye to possess, mani- 

 festly depends both upon its apparent distance 



