THE ARGUMENT APPLIED. 23 



of his means to his end — I will not say to display the com- 

 pass or excellence of his skill and art, for in these all com- 

 parison is indecorous, hut to testify counsel, choice, consider- 

 ation, purpose ? 



To some it may appear a diflference sufficient to destroy 

 all similitude between the eye and the telescope, that the 

 one is a perceiving organ, the other an unperceiving instru- 

 ment. The fact is that they are both instruments. And as 

 to the mechanism, at least as to mechanism being employed, 

 and even as to the kind of it, this circumstance varies not 

 the analogy at all. For observe what the constitution of the 

 eye is. It is necessary, in order to produce distinct vision, 

 that an image or picture of the object be formed at the bot- 

 tom of the eye.* Whence this necessity arises, or how the 

 picture is connected with the sensation or contributes to it, 

 it may be difficult, nay, we will confess, if you please, im- 

 possible for us to search out. But the present question is not 

 concerned in the inquiry. It may be true, that in this and 

 in other instances we trace mechanical contrivance a certain 

 way, and that then we come to something wliich is not me- 

 chanical, or which is inscrutable. But this aflects not the 

 certainty of our investigation, as far as we have gone. The 

 difference between an animal and an automatic statue con- 

 sists in this, that in the animal we trace the mechanism to 

 a certain point, and then we are stopped ; either the mech- 

 anism being too subtile for our discernment, or something else 



* Plate I., Fig. 1. A section of the human eye. It is formed of 

 various coats, or membranes, enclosing pelkicid humors of different 

 degrees of density, and adapted for collecting the rays of light into a 

 focus upon the nerve situated at the bottom of the eyeball : a, is the 

 xqueous hvimor, a tliin fluid like water ; 6, the crystalline lens, of a 

 dense texture ; c, the viti ;ous hmnor, a very delicate gelatinous sub- 

 stance, named from its resemblance to melted glass. Thus the crys ■ 

 rallhie is more dense than the vitreous, and the vitreous more dense 

 than the aqueous humor. They are all perfectly transparent, and 

 together make a compound lens which refracts the rays of light issuing 

 from an object, d, and delineates its figure, e, in the focus 'zpon th? 

 retina, inverted. 



