By mid-December, Darwin saw a similarity between farmers picking the best stock in selective breeding, and a Malthusian Nature selecting from chance variants so that "every part of newly acquired structure is fully practical and perfected", thinking this comparison "a beautiful part of my theory".
By mid-December, Darwin perceived a parallel between farmers selecting superior livestock in selective breeding and Malthusian Nature's process of choosing from random variations so that "every newly formed structure is fully practical and perfected," considering this comparison "a beautiful element of my theory."