336 THE SENSORIAL FUNCTIONS. 



tremity of that nerve. That this effect is actually produced, 

 may be easily shown by direct observation; for if the scle- 

 rotic and choroid coats be carefully dissected off from the 

 posterior part of the eye of an ox, or any other large quad- 

 ruped, leaving only the retina, and the eye so prepared be 

 placed in a hole in a window-shutter, in a darkened room, 

 with the cornea on the outside, all the illuminated objects 

 of the external scene will be beautifully depicted, in an in- 

 verted position, on the retina. 



Few spectacles are more calculated to raise our admira- 

 tion than this delicate picture, which nature has, with such 

 exquisite art, and with the finest touches of her pencil, 

 spread over the smooth canvass of this subtle nerve; a pic- 

 ture, which, though scarcely occupying a space of half an 

 inch in diameter, contains the delineation of a boundless 

 scene of earth and sky, full of all kinds of objects, some at 

 rest, and others in motion, yet all accurately represented as 

 to their forms, colours and positions, and followed in all 

 their changes, without the least interference, irregularity, 

 or confusion. Every one of those countless and stupendous 

 orbs of fire, whose light, after traversing immeasurable re- 

 gions of space, at length reaches our eye, is collected on its 

 narrow curtain into a luminous focus of inconceivable mi- 

 nuteness; and yet this almost infinitesimal point shall be 

 sufficient to convey to the mind, through the medium of the 

 optic nerve and brain, a knowledge of the existence and po- 

 sition of the far distant luminary, from which that light has 

 emanated. How infinitely surpassing all the limits of our 

 conception must be the intelligence, and the power of that 

 Being, who planned and executed an instrument comprising, 

 within such limited dimensions, such vast powers as the 

 eye, of which the perceptions comprehend alike the nearest 

 and most distant objects, and take cognizance at once of the 

 most minute portions of matter, and of bodies of the largest 

 magnitude ! 



