Jeffrey Cramer on Historical Thoreau

Who was the real Henry David Thoreau?  By today's standards, he wasn't an environmentalist or someone who celebrated nature without humans in it.  And "Walden" didn't simply describe his time living by the pond.  He wrote and re-wrote the book over nine years.  Yet his nature writing - and his political essays - have inspired people around the world, from nature lovers to political dissidents.