164 VISION ASSISTED BY THE OTHER SENSES. 



When we look at a round body, the rays oflight proceed 

 only from the side towards us, and yet we never are in 

 doubt of its actual form. We can also judge, with the 

 same degree of accuracy, of the form and size of a book 

 at ten feet distance, as at one, though it is certain that in 

 the former case, the image of the object on the retina is 

 much smaller, and is a plain figure. Objects, in fact, 

 are represented on the retina, in the same manner as in 

 a painting, where, whatever may be their size or figure, 

 they are made with one dimension only ; so that to a 

 person who has just received the sense of sight, external 

 objects appear like the figures in a painting to one if 

 we can suppose such an one wholly ignorant of per- 

 spective. 



Emily. I recollect having read somewhere, an ac- 

 count of a blind person, whose sight was restored by an 

 operation, in which all these facts in regard to vision, 

 were very pleasantly illustrated. I have forgotten the 

 details of the account, and retain only a general impres- 

 sion about it. 



Dr. B. It was probably the one told with delightful 

 naivete by Cheselden, a distinguished English anatomist 

 of the last century, and is quickly related : 



" When he first saw, he was so far from making any 

 judgment of distances, that he thought all objects what- 

 ever touched his eyes, as he expressed it, as what he 

 felt did his skin ; and thought no objects so agreeable 

 as those which were smooth and regular, though he 

 could form no judgment of their shape, or guess what it 

 was in any object, that was pleasing to him. He knew 

 not the shape of anything, nor any one thing from anoth- 

 er, however different in shape and magnitude. Upon 

 being told what things were, whose forms he before 

 knew by feeling, he would carefully observe them that 

 he might know them again ; but having too many ob- 

 jects to learn at once, he forgot many of them, and, as 

 he said, at first he learned to know, and then forgot a 

 thousand things in a day. One particular only, though 



