In November of 1856, Charles Waring Darwin was born, the first child Emma had given birth to in five years. It was soon clear that he was severely retarded. He died a year and a half later when a scarlet fever epidemic raged through Down.
By April 1857, all of Darwin's hard work had made his chronic illness return in full force. He took time off in April for more hydropathy, which he was beginning to think worked only because it relaxed him and forced his mind of work. Nevertheless, he was happy to do anything that could make the pain, nausea, and weakness subside. He worked productively for another year, but on June 18, 1858, he received a letter which instantly set him back: it was a short manuscript from Alfred Russell Wallace, a younger naturalist with whom Darwin had been in contact off and on for several years, and, at first reading, it looked like a carbon copy of Darwin's own theory.
Darwin felt threatened. After Darwin had worked twenty years and waited for the right moment to publish, a young naturalist had come up with the same ideas. He wrote to Lyell for advice. Should he do the honorable thing, sending Wallace's article to the appropriate scientific society and continue to work on his own full-length volume? Or should he try, somehow, to hold onto his claim for having come up with evolution first? Darwin was torn. In the end, Hooker and Lyell decided that Wallace's paper should be presented before the Linnean Society, but Darwin should also contribute a sketch of his own theory. The joint presentation was made on July 1, 1858, with neither Darwin nor Wallace in attendance. Everyone listened politely, but there was neither the kind of outrage that Darwin had feared nor the approval that he had hoped for. Fortunately, Wallace turned out to be happy with the joint presentation; he knew that Darwin had been working on species for years and felt honored to have his work presented alongside Darwin's in front of a prestigious society. Newly galvanized by the fact that Wallace was nipping at his heels, Darwin threw himself into writing an abstract of his longer manuscript for publication.
The abstract covered the same material as the longer manuscript Darwin had started in 1856, but it was pared down to clear, concise prose that stated the basic argument and presented the crucial pieces of evidence in support of it. He argued that species were not created, but rather evolved. He said that the mechanism in charge of directing evolution was natural selection. The first printing of the abstract was put on sale in 1859 under the title On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life. It sold out on the first day.