Since its publication in 1859, The Origin of Species has been the focal point of debate. Darwin's analysis of flora and fauna calls into question the long-held concepts of spontaneous generation, divine creation, and the unrelatedness of many species. Instead, he argues for Natural Selection: species survive and evolve in response to environmental conditions and other circumstances through a process in which those creatures and plants with stronger, more enduring characteristics live to beget more adaptable offspring. It was Darwin's research aboard the H.M.S. Beagle that led to the clash of intellectual titans - religion and science - over the true nature of humankind. Here is the book that started one of the greatest debates of the Western world.