48 BEING AND FACULTIES OF MAN. 



But as the relative positions and relative sizes of our hands, 

 feet, or any portions we see of our own bodies, are correctly 

 given along with the sizes and positions of other objects, 

 we are not conscious of any inconvenience from this fact. 

 Another peculiarity of the eye, which has given a good 

 deal of perplexity and discussion to philosophers, is what 

 some have called the " outness " of vision, or that power of 

 sight by which we perceive solidness in objects and per- 

 spective in space. Some have endeavoured to maintain 

 that the retina was so constructed as to allow images to 

 penetrate its surface to some extent, and therefore show 

 one part of an object a little further back than another. 

 But this explanation is absurd ; for a common mirror or 

 polished metallic surface gives the perspective of images 

 portrayed or reflected on it as correctly as the retina of 

 the eye does, and more correctly than is yet done by 

 photography, for a reason which will presently be ex- 

 plained. And the true solution of the difficulty as to 

 what is called outness of vision is really that images are 

 just as correctly portrayed on the retina of the eye as 

 they are on any ordinary mirroring surface, and that it is 

 not the retina that perceives the perspective so given, but 

 our Consciousness in contact with the surface of the retina, 

 as already mentioned. But as has just been said, a 

 common mirror, and the retina of the eye as well, will 

 give the images and the perspective of objects more 

 correctly than the photographic process yet does ; and 

 the reason for this fact is that in photography a certain 

 amount of distortion and contraction takes place from the 

 circumference to the centre of the image in consequence 

 of the sensitized plate of the photographer being not a 

 concave mirror, like the retina, but a flat surface. This 

 will be in part, but not wholly understood, by re- 

 ferring again to the figure, p. 46, ante, and observing 

 what would be the effect if the retina, instead of being 



