54 BEING AND FACULTIES OF MAN. 



these, and not the retina, convey the images. All that tho 

 retina can do as a mirror is merely to intercept and change 

 the direction of these rays, and it matters nothing, there- 

 fore, whether the Consciousness receives these rays at the 

 surface of the retina or intercepts them elsewhere these 

 rays are ivhat it receives. Berkeley has said that we 

 do not see by geometrical lines, and that our idea of 

 distance cannot be derived from the angularity of these 

 lines, and he has been pleased to treat this proposition 

 with some little ridicule. But that we do not see by 

 geometrical lines is a statement easier to make than to 

 establish. If, as has been just shown, the Consciousness 

 perceives all objects by means of rays proceeding from 

 them, and impinged upon it at the surface of the retina 

 or elsewhere, it is perfectly certain that these rays pro- 

 ceed from the objects in geometrical lines, and that the 

 angularity of these lines and the consequent presentation 

 of the images is affected both by the fact of relative size 

 and the fact of relative distance. It may be a question 

 whether the Consciousness in contact with these rays is 

 extended as a mere surface to receive them at their point 

 of impact, or has depth as well as surface through which 

 the rays angularly penetrate and so aid it in perceiving 

 geometrically : but this question is beyond investigation. 

 What is much more relevant and certain is that the edu- 

 cated eye does perceive geometrical relation in the posi- 

 tion of objects, and that it does so not because the eye, 

 as the effect of education, has acquired any new or improved 

 mode of receiving images or radiation, but merely because 

 the Consciousness has become more capable of appreciating 

 the images received. It must be borne in mind that 

 vision is accomplished from first to last in human beings 

 only in one way, namcl; r , by radiation impinging on our 

 Consciousness with the Vv locity of light, and therefore in 

 a continuous stream of luminous motion affecting our Con- 



