Seeking solitude and self-reliance, Thoreau says, he moved to the woods by Walden Pond, outside Concord Massachusetts, where he lived for two years, writing this book, before returning to society. In the book he sets out his beliefs about society and the nature of human existence, saying first that he believes men need not work as hard as they do, if they are willing to simplify their lives and follow their own instincts. Thoreau designs a life of "voluntary poverty" for himself, determining the absolute necessities of man's existence to be: food, shelter, clothing, and fuel. Criticizing society's spiritually empty obsessions with clothing and elaborate homes, as well as with formal education, travel, and the use of animal labor, he praises the savage man, who is free from the distraction of society's institutions and lives a simple life. Thoreau builds his own small cabin, earns some money by working in his bean-field, and keeps meticulous financial records to demonstrate how little a man needs to live.
When he chooses where to live and moves into his house, he celebrates becoming a part of nature and holds the pond sacred. He went to the woods to "live deliberately," he says, citing simplicity as the path to spiritual wakefulness and taking nature as his model. Discussing his intellectual life, he venerates the written word, calling books the true wealth of nations and urging all people to learn to read well. He believes, more than just reading, that a man must be a seer and listener, constantly alert to nature, and he revels in his solitude, seeing nature as a companion that wards off melancholy. At Walden he receives many visitors, however, as many as 30 at a time, including a Canadian woodchopper, an unsophisticated man who nevertheless impresses Thoreau.
Thoreau's daily work in the bean-field, he says, dignified his existence and connected him to the earth through the ancient art of husbandry. When he wanted some company or some gossip, he often went to the village, where he was once arrested for not paying a tax but was released the next day. Back in the woods, Thoreau describes all the ponds around his house and meets John Field, a man who is too entrenched in his way of life to try a change as Thoreau has. Thoreau discusses the balance in himself between the spiritual life and the savage life, praising self-control and abstinence from eating animal meat. He observes closely the animals of the woods, admiring them for their freedom, and becomes enthralled by a war between red and black ants that happens outside his house.
When winter begins to set in, he builds his chimney and plasters his walls and keeps track of the behavior of the animals and the ice forming on the pond, whose bottom he maps. It begins to get lonely, so for company he imagines the former inhabitants of the woods based on what he knows of them. Spring arrives, melting the ice in certain patterns and bringing with it a reminder of immortality and signs of the union between man and nature. After more than two years, Thoreau leaves Walden transformed by the experience. He urges each man to explore the uncharted territories within him, to obey only the laws of his own being, and to devote his life to the work he cares about, no matter how poor he is. With spiritual awareness and reverence for nature, he says, new life can emerge from within a person.