The Origin of Species introduced the scientific theory that populations evolve over the course of generations through a process of natural selection. It presented a body of evidence that the diversity of life arose by common descent through a branching pattern of evolution. Contents: Variation Under Domestication Variation Under Nature Struggle for Existence Natural Selection Laws of Variation Difficulties on Theory Instinct Hybridism On the Imperfection of the Geological Record. On the Geological Succession of Organic Beings Geographical Distribution Mutual Affinities of Organic Beings: Morphology Recapitulation and Conclusion