# Organs of Extreme Perfection and Complication explained — The Origin of Species > Chapter companion for The Origin of Species by Charles Darwin. ## What happens Darwin addresses the challenge that complex organs like the eye pose to his theory of natural selection. He argues that despite initial incredulity, the existence of numerous gradations from simple to complex eyes, each useful to its possessor, makes it plausible that natural selection could have formed even the most perfect eye. He traces the evolution of the eye from a simple optic nerve with pigment to the complex vertebrate eye, emphasizing that reason must overcome imagination in accepting this process. ## Themes in this chapter ### Natural Selection and the Struggle for Existence Central theme: Darwin argues that natural selection can form even the most perfect organs through gradual, useful steps. ### Variation and Inheritance Key to the argument: variations in the eye are inherited, and natural selection acts on them over generations. ### Adaptation and the Utilitarian Doctrine Each gradation of the eye must be useful to its possessor, upholding the utilitarian principle in evolution. ## Character check-ins ### Charles Darwin Author and primary voice, defending natural selection against the objection of complex organs. ### Mr. Wallace Quoted on how different modifications can improve the eye, supporting gradual change. ### Professor Owen Cited for his observation on the range of gradation of dioptric structures in fishes and reptiles. ### Mr. Mivart Implied as an objector to the theory, as Darwin addresses objections to simultaneous modifications. ## Key lines > 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. Darwin admits that the idea of the eye evolving through natural selection seems utterly absurd at first glance. _Opening concession to the difficulty of the argument._ > 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. Darwin argues that if gradual, useful variations exist and are inherited, then natural selection can explain the eye's evolution despite imaginative resistance. _Core logical defense of natural selection against the eye objection._ > We must suppose each new state of the instrument to be multiplied by the million; each to be preserved until a better is produced, and then the old ones to be all destroyed. Darwin envisions natural selection as a process where each improved eye variant is preserved and multiplied, while inferior versions are eliminated. _Illustration of the cumulative, selective process over vast timescales._ ## Links - HTML: https://www.betterreads.online/discover/the_origin_of_species_se/chapters/organs-of-extreme-perfection-and-complication - Book: https://www.betterreads.online/discover/the_origin_of_species_se - All chapters: https://www.betterreads.online/discover/the_origin_of_species_se/chapters