Leaves Of Grass, by Walt Whitman

Why?

"This book was like The Americans, it was a view of America. And, it blew my gasket, it just blew my mind, because for the first time I was seized by this craving, by this compulsion to travel, to see that multitude that what Whitman had seen, to experience this sort of inflation of life, this, I don't know, this just enthusiasm that he had encountering the world."
- Kevin Kelly, co-founder of Wired