SINGLE VISION. ' 



Such is the solution which Dr. Smith has 

 given of this celebrated question, and such the 

 reply which his general account of vision fur- 

 nishes to one objection against it. But there 

 are others which, in my opinion, cannot be so 

 easily repelled. Before I offer these, however, 

 I beg leave to remark, that although it were 

 proved, as I think it maybe, that he is mistaken 

 in the fact of objects appearing single, when 

 their pictures fall upon the middle or other 

 corresponding points of the retinas, still the 

 truth of what is peculiar to him * of the solu- 

 tion he gives, might remain unshaken. Ob- 

 jects, it may be said, are constantly seen single 

 when we direct our eyes to them in a particular 

 manner. Their pictures must, consequently, 

 in every such case, fall upon the same places of 

 the retinas ; and whether these be correspond- 

 ing or not, the unity of the visible appearances 

 will be owing to the connexion, which has uni- 

 formly been observed between the sensations of 



* Dr. Reid attributes to Bishop Berkeley the opinion, 

 that objects appear single to two eyes, from an experienced 

 connexion between particular sensations of sight, and the 

 informations of touch. But I no where find it mentioned in 

 the works of that author j and I even think it probable, that 

 he purposely avoided treating of the question, as he found 

 that the solution of it, which naturally flowed from his prin- 

 ciples of vision, was with difficulty to be reconciled to other 

 conclusions he had derived from the same source. 



