^6 NATCJilAL THEOLOaY. 



as the depth of the eye is called, is elongated. These changes 

 in the eye vary its power over the rays of light in sucli a 

 manner and degree as to produce exactly the effect which 

 is wanted, namely, the formation of an image U'pon the reti' 

 na, whether the rays come to the eye in a state of divergen- 

 cy, which is the case when the object is near to the eye, or 

 some parallel to one another, which is the case when the 

 object is placed at a distance. Can any thing be more deci- 

 sive of contrivance than this is ? The most secret laws of 

 optics must have been known to the author of a structure 

 endowed with such a capacity of change. It is as though an 

 optician, when he had a nearer object to view, should rectify 

 his instrument by putting in another glass, at the same tim.e 

 drawing out also his tube to a different length. 



Observe a new-born child first lifting up its eyelids. What 

 does the opening of the curtain discover ? The anterior part of 

 two pellucid globes, which, when they come to be examined, 

 are found to be constructed upon strict optical principles — 

 the selfsame principles upon which we ourselves construct 

 optical instruments. We find them perfect for the purpose 

 of forming an image by refraction ; composed of parts exe- 

 cuting different offices ; one part having fulfilled its office 

 upon the pencil of light, delivering it over to the action oi 

 another part ; that to a third, and so onward : the progressive 

 action depending for its success upon the nicest and minut- 

 est adjustm^ent of the parts concerned ; yet these parts so in 

 fact adjusted as to produce, not by a simple action or effect, 

 but by a combination of actions and effects, the result which 

 is ultimately wanted. And forasmuch as this organ would 

 have to operate under different circumstances, with strong 

 degrees of light and with weak degrees, upon near objects 

 ind upon remote ones, and these differences demanded, ac- 

 cording to the laws by which the transmission of light is 

 regulated, a corresponding diversity of structure — that the 

 aperture, for example, through which the light passes should 

 be larger or less — the lenses rounder or flatter, or that theii 



