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formation of the eye, he tries his system by another crucial instance— the 
instinct which leads the hive-bee to construct its marvellous geometrical cell 
By these two instances, challenged by Mr. Darwin himself, would I test his 
hypothesis, and try not the truth, but the credibility, in Mr. Warington’s 
sense, of the system. How upon this system is so complex an organ as the 
eye formed ? The primordial being of Darwin is not formed with any eye from 
which our own may trace its ancestry. It is to be traced back to an organ 
not optical at all, or made with any reference to the laws of light— but to 
the mere chance exposure of a nerve of sensation to the influence of light . In 
making our first step backwards from the human eye, Mr. Darwin tells us it is 
not a perfect optical instrument— that it is imperfect in achromation. Now, 
though I am aware that Sir D. Brewster is stated to have admitted that the 
eye is imperfect as an achromatic instrument, I would venture to question 
that assertion. I know that my own eyes are not now perfectly achromatic ; 
but they once were so — as I know by my own experience. But they have 
acquired this defect, as they have that of short-sightedness, by an abuse of 
their proper use. I assert that the human eye is a most complex organ, 
regarded as an optical instrument — that it combines in one all that man 
strives humbly and vainly to imitate, in a perfectly achromatic microscope, 
telescope, and camera obscura. I maintain that all the conditions which pure 
mathematical science can demonstrate as necessary for destroying spherical 
or chromatic aberration in the differing densities, curvature, and distances of 
lenses, are perfectly fulfilled in the human eye ; that, too, in a manner 
defying the imitation of human art. And why ? Because man cannot make 
a lens out of a substance varying in refracting powers. He cannot even 
grind his lenses to the proper curvature which his mathematical analysis 
teaches him to be necessary. But such defects are not to be found in the 
workmanship of the eye. I therefore take the eye, as I believe I have a 
right to do, on sound scientific principles, as a perfect optical instrument. I 
say nothing of the secretion of that black pigment which absorbs the super- 
fluous rays of light. I say nothing of that marvellous mechanism which 
changes the curvature of the lenses of the eye in a manner no human 
instrument can ever do. I say nothing of the iris — that varying diaphragm so 
sensitive to light, not for vision but for contractibility — which admits into the 
camera obscura of the eye just that amount of light which is necessary for 
the perfection of the image on the retina. I take this marvellous instrument, 
and I am told by Mr. Darwin that his system must collapse, that his 
hypothesis must crumble to dust, unless I can believe, as a thing within 
the range of credibility, that this perfect instrument has originated without 
a designer. For this is the force of Mr. Darwin’s argument— that these 
lenses, so perfectly adapted to the laws of light, in geometrical form and 
refractive powers on the rays of light, with all the marvellous mechanism 
for adapting them for near and distant vision, manifest no unanswerable 
evidence of design — that it is credible that all this marvellous combination 
and perfect adaptation to the laws of light are due to no forethought— no 
design— no wisdom. That all this has been formed simply by the law of 
