These pages include the final edition of Charles Darwinu2019s groundbreaking work that introduced the theory of evolution by means of natural selection.nnFirst published in 1859, Charles Darwinu2019s On the Origin of Species introduced the scientific theory of evolution by means of natural selection, a revolutionary idea at the time. Fiercely debated on its release, Darwinu2019s famous work was revised several times over the following decade, partly to refute the scientific and religious objections of the authoru2019s contemporaries. In this sixth edition of On the Origin of Species, Darwin lays out his theory by citing his studies done in the Galápagos aboard the HMS Beagle in the 1830s, as well as his follow-up research over the ensuing two decades.