In the sixth chapter of On The Origin of Species, Charles Darwin addresses "Organs of Extreme Perfection" – organs like the eye, the formation of which due to natural selection, Darwin "freely confessed," seems "absurd in the highest possible degree." But this is only part of a much longer quote.

The sentence is almost always cherry-picked from its context. Sometimes, it's by creationists. Other times it's by well-intentioned videos like this one, which was released this week by the folks at TED-Ed:

As much as I enjoyed this video (it winds up illustrating Darwin's larger point with its own examples), the problem with presenting the quote out of context is that it suggests Darwin concurred with the watchmaker analogy, a teleological argument that insists a complex design – whether it's a watch, an eye, the human form, or life as we know it – implies the existence of some designer. In fact, the full quotation demonstrates Darwin's thoughts on the matter to be quite the opposite:

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. When it was first said that the sun stood still and the world turned round, the common sense of mankind declared the doctrine false; but the old saying of Vox populi, vox Dei, as every philosopher knows, cannot be trusted in science. Reason tells me, that if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certainly the case; if further, the eye ever varies and the variations be inherited, as is likewise certainly the case; and if such variations should be useful to any 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, should not be considered as subversive of the theory. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself originated; but I may remark that, as some of the lowest organisms, in which nerves cannot be detected, are capable of perceiving light, it does not seem impossible that certain sensitive elements in their sarcode should become aggregated and developed into nerves, endowed with this special sensibility.

That which seems absurd can be shown to be sensible, if observation and reason dictate.