1838, he had arrived at a sketch of a theory of evolution through natural selection (Encarta). Since Darwin was individually wealthy and did not have to work for money, he was able to work on his idea of evolution for two whole decades.
             In 1859, after twenty-one long years of work, Darwin finished his theory and published it in On the Origin of Species. "Often referred to as the 'book that shook the world,' the Origin sold out on the first day of publication and subsequently went through six editions (Funk 43)."
             Darwin's theory of evolution by natural selection is basically that the young born to any species is complete for survival, and those young that survive to produce the next generation tend to characterize favorable natural variations, and these variations are passed on by heredity, and so on (Encarta). "Therefore, each generation will improve adaptively over the preceding generations, and this gradual and continuous process is the source of the evolution of species (Encarta)." Before the theory of evolution, most geologists believed that a set of creatures would be born, then a catastrophe would occur, and a new species would be born, and then another catastrophe, and so on. This idea was called the catastrophist theory.
             Some biologists complained that Darwin was unable to prove his ideas and others complained that he couldn't explain the origin of variations or how they were passed on by heredity. In the early 20th century, because of modern genetics, Darwin's ideas were backed up by tons of evidence. Because his ideas rejected those of creationism, many more religious opposed to scientific people objected to his ideas.
             Darwin spent the rest of his life expanding on different aspects of problems raised in the Origin. Darwin died in Downe, Kent, on April 19, 1882.
             William Jennings Bryan, born on March 19, 1860, in Salem, Illinois, was a U.S. congressman, a three-tim...