SENSE OF SIGHT. 223 



sown field, without frightening the animal; and when at 

 length he suddenly disappeared, no tracks or traces of him 

 could be discovered on the soft mould. Nothing could con- 

 vince the old gentleman that his sight had deceived him, 

 that these objects had only existed in his brain. 



53. One source of deception lies in the fact that, indirect 

 as well as direct vision is intermittent, as any one may 

 learn by attempting to read small print by moonshine, or in 

 twilight, or by looking at a single star for some time, when 

 it will be found to vanish often and reappear. In an ob- 

 scure light we find that a painful effort is required to distin- 

 guish objects ; and after all they appear and disappear, be- 

 cause the impression they make upon the retina is not 

 sufficiently vivid to be continuous. We can easily imagine 

 therefore, that in the dusk, to a person who is ignorant of 

 this fact, the sudden disappearance and reappearance of 

 objects must seem very extraordinary. 



54. Dr. Paley remarks that, " were there no example in 

 the world of contrivance except that of the eye, it would be, 

 alone, sufficient to support the conclusions which we draw 

 from it, as to the necessity of an intelligent Creator." When 

 we look at a telescope, and see how it consists of a tube 

 composed of various pieces, containing several glasses or 

 lenses placed at different distances in order to refract the 

 rays of light, and bring them to a focus ; how, within it, 

 there is a partition of metal, through which is a round hole 

 in the centre for the purpose of lessening the surface of the 

 lens on which the rays of light strike ; and when, in addi- 

 tion to all this, we see the inside painted black, to absorb the 

 oblique and scattering rays that would otherwise render 

 objects confused and indistinct; when we see all these 

 things, we immediately say, here are marks of design, here 

 is evidence of wise and skilful contrivance ! and yet the 

 telescope is but a close imitation of the human eye, which 

 had God for its designer. When, also, we look at the ca- 

 mera obscura and see a tight, dark box, with a lens fitted in- 



