what is Thoreau searching for that he cannot fin in civilization

Living in a society in which man ­ in the form of railroads, factories, and other technical innovations ­ had begun to tame and control nature, Thoreau counters the separation of man from society by conceiving of man as a part of nature. Through his life in the woods, living for the most part off the fruits of the land and deriving intellectual stimulation from plants and animals, Thoreau demonstrates that man can live successfully in the midst of nature. The animals give him companionship and accept him as a familiar part of their environment. Even nature itself is empathetic to him, for example waiting to blow its coldest winds after Thoreau builds his chimney and plasters his walls. The assertion that man is part of nature promotes Thoreau's suggestion that most people who be more intellectually fulfilled and spiritually aware away from the smothering cocoons of city and village life.