This video from the USA says about him:
31 May 2009
“In wildness is the preservation of the world,” wrote Henry David Thoreau in 1851 at a time when he was one of the few thinking about environmental conservation. Six years previous he had embarked on a now-famous experiment in simple living. He’d gone to the woods outside Boston to live in a 150-square-foot cabin to avoid living “what was not life”. …
He spent two years, two months and two days in his cabin at Walden Pond and in 1854, he published his reflections on life in the woods in the book Walden. The book is credited with helping to inspire environmental awareness. …
Due to his detailed observations of the natural world during his days at Walden, his work is now being used to help modern scientists study climate change.
When he died in 1862, the industrial revolution was just beginning to pump greenhouse gases into the atmosphere. His recordings of when and where plants flowered in the area are now being studied to show patterns of climate change.
Conservation biologists reported in 2008 – based on Thoreau’s research- that common species are flowering 7 days earlier than they did during his day and 27% of the species he studied have disappeared (another 36% are endangered).
Henry David Thoreau did not only inspire environmentalism in the USA, but also in many other counties. This morning, Dutch Vroege Vogels radio said that without Thoreau, famous Naardermeer nature reserve would now be a landfill.
Thoreau was also a big influence on literature, both in the USA and elsewhere. Walden, the name of Thoreau’s cabin and book, became the name for the Walden utopian socialist community in the Gooi region as well; founded by Dutch poet Frederik van Eeden.
From the site of The Thoreau Society in the USA:
Thoreau Bicentennial Gathering: Celebrating the Life, Works, and Legacy of Henry David Thoreau
The Thoreau Society Annual Gathering & Bicentennial Celebration of
Thoreau’s Life, Works, and Legacy
July 11-16, 2017
Be it life or death, we crave only reality.
Henry D. Thoreau