ON THE RELATION OF OPTICS TO PAINTING. 79 



vivid perception of any particular aspect of human 

 existence in its complete and unhindered development. 



If however the artist is to produce an artistic 

 arrangement of only idealised types, whether of man 

 or of natural objects, must not the picture be an 

 actual, complete, and directly true delineation of that 

 which would appear if it anywhere came into being ? 



Since the picture is on a plane surface, this faith- 

 ful representation can of course only give a faithful 

 perspective view of the objects. Yet our eye, which 

 in its optical properties 'is equivalent to a camera 

 obscura, the well-known apparatus of the photo- 

 grapher, gives on the retina, which is its sensitive 

 plate, only perspective views of the external world ; 

 these are stationary, like the drawing on a picture, 

 as long as the standpoint of the eye is not altered. 

 And, in fact, if we restrict ourselves in the first place 

 to the form of the object viewed, and disregard for 

 the present any consideration of colour, by a correct 

 perspective drawing we can present to the eye of an 

 observer, who views it from a correctly chosen point 

 of view, the same forms of the visual image as the 

 inspection of the objects themselves would present to 

 the same eye, when viewed from the corresponding 

 point of view. 



But apart from the fact that any movement of the 

 observer, whereby his eye changes its position, will 



