Charles Darwin looked closely at life. The vast and marvelous diversity of life on Earth, from barnacles to butterflies, ostriches to orchids, made him curious. Countless species, living and extinct—why so many? Some were only slightly different from one another-what could explain that? Each organism so beautifully adapted to its environment—how could it happen?

With persistence and passion, Darwin set out to find answers. He conducted experiments. He read widely and corresponded with fellow naturalists around the world. And he studied the evidence using simple tools, at times little more than a microscope or a magnifying glass. Darwin looked closely—and we saw the world in a new way.