"Walden. Yesterday I came here to live". That entry from the journal of Henry David Thoreau, and the intellectual journey it began, would by themselves be enough to place Thoreau in the American pantheon. His attempt to "live deliberately" in a small...

Explorer, scientist, writer, and humanist, Alexander von Humboldt was the most famous intellectual of the age that began with Napoleon and ended with Darwin. With "Cosmos", the book that crowned his career, Humboldt offered to the world his vision of...