More than any book, this argues for experiencing nature and preserving wilderness. Thoreau himself saw that fewer passenger pigeons were visiting and even then was aware of threats. Though first spoken in lectures on 1851, and 1856-1857, and published in June 1862 Atlantic Monthly, a month after his death, it still speak to us in the 21st century. For example “.. what would become of us, if we walked only in a garden or a mall?”, . “In wilderness is the preservation of the world.” , “To preserve wild animals implies generally the creation of a forest for them to dwell in or resort to. So it is with man”. So lace up your shoes, grab your binoculars, and go for a walk and join the tribe of squirrels!