Explorer. Scientist. Polymath. Hero. In his day, Alexander von Humboldt (1769–1859) was among the most renowned scholars of the Enlightenment. He led pioneering expeditions in Central and South America (including the Amazon rainforest) as well as in Siberia, and he arguably founded the natural sciences as we know them. Charles Darwin called Humboldt “the greatest scientific traveler who ever lived,” and credited him with inspiring the journey that resulted in On the Origin of Species. And yet, in history books, Humboldt has been eclipsed by his intellectual heirs and admirers—such as Darwin himself, John Muir, and Henry David Thoreau—until now.