Henry David Thoreau's Walden; or, Life in the Woods describes his experience of living in a cabin in the woods by Walden Pond in Massachusetts. The book details Thoreau's spiritual quest to live independently and simply and to transcend the desperation that he perceives to be a core part of most people's existence. In discovering his connection with nature and refusing the quest for outward success, Thoreau connects transcendentally to the concept of self-reliance and minimizes his lifestyle and needs.
Ultimately, he chooses to leave Walden Pond, stating:
I left the woods for as good a reason as I went there. Perhaps it seemed to me that I had several more lives to live, and could not spare any more time for that one. It is remarkable how easily and insensibly we fall into a particular route, and make a beaten track for ourselves. I had not lived there a week before my feet wore a path from my door to the pond-side; and though it is five or six years since I trod it, it is still quite distinct. It is true, I fear, that others may have fallen into it, and so helped to keep it open. The surface of the earth is soft and impressible by the feet of men; and so with the paths which the mind travels. How worn and dusty, then, must be the highways of the world, how deep the ruts of tradition and conformity!
In other words, his life in the woods was becoming tired--a path well-trod and too familiar. In order to continue his transcendence, Thoreau would have to once again leave behind the comfortable in search of something greater, believing that if one stays in any one place for too long, he risks falling into a state of conformity.
Thoreau basically says that he came to the pond for certain reasons and now they are satisfied, and so is he. His job there was done. There were other things to do, and so he left.
Specifically, he quotes, "I left the woods for as good a reason as I went there. Perhaps it seemed to me that I had several more lives to live, and could not spare any more time for that one. It is remarkable how easily and insensibly we fall into a particular route, and make a beaten track for ourselves." He did not want living in the woods to become a mere habit, and felt there were other goals in life he was to pursue and achieve.
He has realized his dreams, and at the conclusion of Walden, he suggests that readers, rather than pursue success, should go their own ways at their own pace and love their lives no matter how humble those lives may be.