I think the answer would be Thoreau actually lived alone in nature for 2 years.
Thoreau likes nature very much. He built himself a cabin along Walden Pond. He is a big believer in individualism and has very big respect in regards to the environment. He has written Walden, a compilation of his experience living with nature's best gift. He also wrote Civil disobedience, wherein he shapes the concept of freedom and what should be the role of the people towards the government.