This lecture takes readers inside Charles Darwin’s Origin of the Species and shows why it can fairly claim to be the greatest science book ever published. An immediate and influential sensation in 1859, the book sold its first print run in one day and profoundly shocked Victorian readers with its description of evolution through natural selection. Janet Browne, widely acclaimed as “Darwin’s biographer,” explains Darwin’s readings as a university student, his five-year voyage on the Beagle, his experiments in his home and garden, his correspondence and debates with other naturalists, and his urgency to publish his theory of evolution.Janet Browne is Aramont Professor of the History of Science at Harvard University where she teaches the history of natural history and biology. In 2002 she published a two-volume biography of Charles Darwin, and in 2006 Darwin’s Origin of Species: A Biography. Her interest in Darwin stems from her time as an editor on the Darwin Correspondence Project, Cambridge, England.