62 Natural TJieology. 



special wants. But as we are considering the rela- 

 tions of man to the world, we need not pass beyond 

 our subject to find arguments for design. The eye 

 of man, though limited in its power to a certain 

 range, gives all that the common wants of life de- 

 mand. And if man needs greater range of vision, 

 he has but to study the eye itself, and fashion instru- 

 ments to increase its power ; as he is able when the 

 proper time has come in his civilization, to increase 

 by science and art the efficacy of nearly all his phy- 

 sical powers. For the ordinary purposes of life, 

 neither telescopic nor microscopic adjustment of the 

 eye is needed. 



But the eye has not only the power of vision 

 so necessary to man, but it is an instrument of 

 power, an instrument made up of distinct parts, of 

 soljds and liquids, of transparent and opaque tissues, 

 of curtains, and lenses, and screens. Its mechanism 

 can be accurately examined and the use of each 

 part as perfectly understood as any of the works of 

 man. We examine every part of it as we would a 

 microscope. We have first the solid case which is 

 to hold all the machinery, and upon which are to be 

 fastened the cords and pulleys of its skilful mount- 

 ing. This covering, opaque, white, and glistening, 

 like silver on the back and sides of the eye, in front, 

 where the light must enter, suddenly becomes trans- 

 parent as the clearest crystal. Within this is a 

 second coating, that coming to the front changes 

 just as suddenly into an opaque screen, through the 

 tissues of which no ray of light can pass. That 



