Organs of extreme Perfection and Complication. To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.
But, as usual, Christians are taking things out of context. Charles Darwin wrote these words in order to draw his opponents closer so that when the punch came it would be all the more effective. Here's how Charles Darwin explains the evolution of the human eye:
Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.
How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound.
In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted from the earlier stages of descent, in an unaltered or little altered condition. Amongst existing Vertebrata, we find but a small amount of gradation in the structure of the eye, and from fossil species we can learn nothing on this head. In this great class we should probably have to descend far beneath the lowest known fossiliferous stratum to discover the earlier stages, by which the eye has been perfected.
Charles Darwin goes on for another three pages explaining how the human eye evolved. Charles Darwin was not confused or baffled how his theory could have encompassed the evolution of the human eye.
A very good picture is drawn by Richard Dawkins of how evolution works, and here is how it goes:
To assume that evolution is a one-step chance process is like standing at the bottom of Mt. Improbable and trying to leap to its summit ten thousand feet straight up a cliff. This is absurd and unlikely to ever happen. However, on the back side of the mountain is a very gradual slope.
Creationists try to convince everyone that evolution is an immediate process and that they should shy-away from ever reading about it, because Satan is trying to get into their heads. This is a very effective way of keeping the flock ignorant, so I must admit, in the big picture, the priests are doing a great job scaring their flock.
Creationists like to talk about something called "irreducible complexity", or IC. IC says that an object, organ or other item is irreducibly complex if the removal of one of its parts or functions causes the entire object to fail and become useless. This assumes that there can not be degrees of complexity.
However, looking at the eye of the flatworm, which only shows light and shadow, but no shapes, it is easy to see how this eye, which could be called 25% of the human eye, benefits the flat worm. The nautilus has a pinhole-camera eye which shows shapes and objects, but through a very dim and blurry haze. Even then, the nautilus' eye can still easily be understood to be at least 50% of a human's eye.
Creationists: Evolution is not chance. It is a gradual, selective process which is very elegant and explains biological evolution. Learn more about it before you look silly like these people who misquoted Charles Darwin for their own gain. Christians are supposed to be honest, but these ones are either ignorant or very dishonest indeed:
http://carm.org/charles-darwin-on-the-human-eye (Apologetics Website)
http://www.detectingdesign.com/humaneye.html (Medical Doctor)
http://www.overcomeproblems.com/believe_in_evolution.htm (Just some weak private website.)
http://www.truenews.org/Creation_vs_Evolution/natural_selection.html (True news?! False news.)
This rumor that Charles Darwin couldn't explain the human eye is 50% lie and 50% laziness. Don't be one of the lazy, lying people like the examples above.