In "Conclusions," in Walden, explain the message of the story about the traveler and the boy in the swamp.
In the final section of this impressive philosophical tome, Thoreau points out the superfluous nature of so much of society. He argues that wealth we have that is extra will only ever buy us things we don't really need. Again and again he returns to his central argument that is that money is not essential or necessary to provide for the needs of the soul. He talks about the various dinner parties that occur in the city and the amusing anecdotes that are being told and compares these frivolities of society with a swamp where you might find the bottom independently:
There is a solid bottom everywhere. We read that the traveller asked the boy is the swamp before him had a hard bottom. The boy replied that it had. But presently the traveller's horse sank in up to the girths, and he observed to the boy, "I thought you said that this bog had a hard bottom." "So it has," answered the latter, "but you have not got half way to it yet." So it is with the bogs and quicksands of society; but he is an old boy that knows it.
Society, Thoreau argues, is essentially superficial and meaningless in so many ways. Whilst there is a rock bottom to it, it is covered in swamp that will bog us down. We can reach the bottom, but we have to discover it for ourselves and penetrate through the superficiality that governs our society.