His food during his twenty-six months of residence there cost him twenty-seven cents a week. "I learned," he says, "from my two years' experience that it would cost incredibly little trouble to obtain one's necessary food, even in this latitude; that a man may use as simple a diet as the animals, and yet retain health and strength.... I am convinced both by faith and experience that to maintain one's self on this earth is not a hardship, but a pastime." This book has, directly or indirectly, caused more to desire the simple life and a return to nature than any other work in American literature. In _Walden_ he speaks of himself as a "self-appointed inspector of snowstorms and rainstorms." His companionship with nature became so intimate as to cause him to say, "Every little pine needle expanded and swelled with sympathy and befriended me." When a sparrow alighted upon his shoulder, he exclaimed, "I felt that I was more distinguished by that circumstance than I should have been by any epaulet I could have worn." When nature had some special celebration with the trees, such as decking them with snow or ice or the first buds of spring, he frequently tramped eight or ten miles "to keep an appointment with a beech-tree or a yellow-birch, or an old acquaintance among the pines." It is amusing to read how on such a walk he disturbed the daytime slumbers of a large owl, how the bird opened its eyes wide, "but their lids soon fell again, and he began to nod," and how a sympathetic hypnotization began to take effect on Thoreau. "I too," he says, "felt a slumberous influence after watching him half an hour, as he sat thus with his eyes half open, like a cat, winged brother of the cat." In spite of some Utopian philosophy and too much insistence on the self-sufficiency of the individual, _Walden_ has proved a regenerative force in the lives of many readers who have not passed the plastic stage. The book develops a love for even commonplace natural objects, and, like poetry, discloses a new world of enjoyment. _Walden_ is Thoreau's most vital combination of his poetic apprehension of wild nature with his philosophy and aggressive individualism. Almost all of his work is autobiographical, a record of actual experience. _The Maine Woods_ (1864), _Cape Cod_ (1865), and _A Yankee in Canada_ (1866) are records of his tramps in the places named in the titles-, but these works do not possess the interest of _Walden_.