I once drove Dr. John Henrik Clarke home. It was about an hour's drive to Harlem, and we talked the whole way. He was already elderly by then, his eyesight failing, but his mind was as sharp as a blade. There was nothing frail about the way he thought or the way he...

They told you Columbus discovered America in 1492. They told you that before Europeans arrived, the Americas were isolated — cut off from the rest of the world, waiting to be "found." They told you Africans had no ships. No navigation. No capacity to cross oceans....