Walking opens by announcing its bias. Thoreau says he wishes to speak a word for Nature, for absolute freedom and wildness, as against a merely civil freedom, and to regard a person as a part of Nature rather than a member of society. He admits this is an extreme statement made to balance the many champions of civilization.
From there he develops the art of walking, which he prefers to call sauntering. He plays with the word's derivation, from those who roved toward the Holy Land, to argue that a true walker is at home everywhere and bound nowhere. He claims he cannot keep his health unless he spends hours each day walking free of all worldly engagements, and he pities the shopkeepers who sit indoors from morning to night.
The essay's middle turns to direction. Thoreau notices that when he sets out without a destination he drifts toward the southwest, and he treats this private compass as a sign of a larger human tendency to move westward toward the wild and the future. The West, for him, is only another name for the Wild, and it is there that he locates hope, vigor, and what is still to be discovered.
This leads to the book's most quoted thought: that in wildness is the preservation of the world. Thoreau argues that nations and individuals alike draw their strength from wild sources, that the tonics of life come from the forest and the swamp, and that an over-tamed culture grows weak. He praises the value of marshes, wild apples, and a knowledge that is closer to instinct than to the lecture hall.
Near the end he distinguishes a useful, beautiful ignorance from a conceited knowledge that robs a person of wonder, and he asks that we learn to live in the present and to bathe in atmospheres unknown to our feet. The essay closes on an autumn evening, the walkers sauntering toward their own Holy Land as a serene golden light promises a great awakening.