Darwin's most important work introducing the scientific theory that populations evolve over the course of generations through a process of natural selection. It presents a body of evidence that the diversity of life arose by common descent through a branching pattern of evolution. Darwin includes evidence that he had gathered on the Beagle expedition and his subsequent findings from research, correspondence, and experimentation. The book was written for non-specialist readers and attracted widespread interest upon its publication. As Darwin was an eminent scientist, his findings were taken seriously and the evidence he presented generated scientific, philosophical, and religious discussion.