re: Mary Lou's found quote:
"A man is rich in proportion to the number of things which he can afford to let alone."
I think Thoreau is making light/fun-of that a rich man leaves many things he has untouched, where a poor man must use up everything they have. (Thoreau seems much in favor of only producing/using what you need and nothing more).
Here is another quote which seems to be a common theme of Mr. Thoreau:
"Let not to get a living be thy trade, but thy sport".