Charles Darwin was a British naturalist and geologist, best known for his vast contribution to evolutionary theory. He theorised that every living species descended, over time, from various common ancestors; he also helped establish the scientific notion widely referred to as natural selection. Darwin later published his theory, entitling the book: The Origin of Species; in just over ten years, from the date of publication, his evolutionary theory was considered by the general public as fact. He later examined human evolution and once again published his findings in his book, The Descent of Man. Another book deserved of mention is Darwin's Voyage of the Beagle, a vibrant and exhilarating travel memoir which scientifically details the five years he spent traversing the world's lands and seas; a publication that brought him both great fame and popularity.