VISUAL PERCEPTIONS. 521 



of a question which has frequently been sup- 

 posed to involve considerable difficulty ; namely, 

 how it happens that we see objects in their true 

 situation, when their images on the retina, by 

 which we see them, are inverted. To expect 

 that the impression from an inverted image on 

 the retina should produce the perception of a 

 similar position in the object viewed, is to com- 

 mit the error of mistaking these images for the 

 real objects of perception ; whereas they are only 

 the means which suggest the true perceptions. 

 It is not the eye which sees; it is the mind. The 

 analogy which the optical part of the eye bears 

 to a camera obscura has perhaps contributed to 

 the fallacy in question ; for, in using that instru- 

 ment, we really contemplate the image which is 

 received on the paper, and reflected from it to our 

 eyes. But in our own vision nothing of this kind 

 takes place. Far from there being any contem- 

 plation by the mind of the image on the retina, 

 we are utterly unconscious that such an image 

 exists ; and still less can we be sensible of the 

 position of the image with respect to the object. 

 All that we can distinguish as to the locality of 

 the visual appearance which an object produces, 

 is that this appearance occupies a certain place 

 in the field of vision ; and we are taught, by the 

 experience of our other senses, that this is a sign 

 of the existence of the external object in a parti- 

 cular direction with reference to our own body. 



