John Murray's London publishing house released 1,250 copies of Charles Darwin's On the Origin of Species by Means of Natural Selection, which sold out on its first day. Drawing on decades of observation, including his 1830s voyage aboard HMS Beagle, Darwin argued that species evolve through a process of variation and selective survival rather than fixed divine design, a claim that ignited fierce theological and scientific debate.
Darwin had sat on his theory for roughly twenty years, terrified of the backlash, before a letter from fellow naturalist Alfred Russel Wallace describing a strikingly similar idea forced his hand. Friends arranged for both men's work to be presented jointly at the Linnean Society in 1858, and Darwin then rushed to finish what he called an 'abstract' of his fuller argument—the book that became Origin of Species.
The first edition ran just over 500 pages and never once used the word 'evolution.' Its final line, however, became one of science's most quoted: he described life evolving from simple beginnings into 'endless forms most beautiful and most wonderful.' Reaction was immediate and polarized—Cambridge geologist Adam Sedgwick called it a book that would cause 'grievous' moral harm, while Thomas Huxley became its fierce public defender, earning the nickname 'Darwin's bulldog.' The book never went out of print and remains a founding text of modern biology.