Henry David Thoreau (1817-1862) was a naturalist, essayist, poet, and philosopher. Thoreau's literary style combines the observation of nature with personal experience, symbolic meaning, and historical lore. His books, articles, essays, journals, and poetry amount to more than 20 volumes. 

Book One: Walden is an account of the time Thoreau lived alone in a cabin in Concord, Massachusetts. He built the cabin, grew and sold vegetables, and contemplated consciousness and identity. The theme is simple living in natural surroundings, and in essence, the work may be seen as a declaration of independence, a social experiment, quest of spiritual discovery, and a self-reliance guide. 

Book Two: In the essay, "On the Duty of Civil Disobedience",Thoreau contends that an individual should not permit a government to overrule their conscience. He argues that one’s conscience ought to take priority over the law, in order to avoid becoming an agent of injustice. He was partly motivated by the institution of slavery and by the Mexican American war of 1846-1848. 

Book Three: The themes of Thoreau’s essay "Walking" include freedom, self-reflection, and exploration. Thoreau reminds us of how the primal act of walking connects us with nature, stating that the act of walking marks the human being as an inhabitant, or part and parcel of nature, rather than a member of society. 

Book Four: The Maine Woods recounts three trips Thoreau took by boat and canoe through the wild interior; it describes the rivers and forests of Maine, the customs of woodsmen and Indian guides, and the effects of the timber industry and encroaching settlements on the pristine land. 

Book Five: In Cape Cod (1865), Thoreau recounts his walking trips along a stretch of Massachusetts coastline, including Cape Cod, in the 1850s. The narrative is filled with his reflections on the elemental forces of the sea and the shore. Sleeping in lighthouses and fishing huts, and on isolated farms. Cape Cod is an engaging and funny account of 19th-century life on the Cape long before it became a popular tourist destination. 

Book 6: A Week on the Concord and Merrimack Rivers describes the Thoreau brothers' river journey on the Concord River from Concord to Lowell, Massachusetts and on the Merrimack River from Lowell north to Concord, New Hampshire. 

Book 7: The Service is in part a contrarian swipe at the many pacifist writers and lecturers whose teachings on "non-resistance" were then very much in vogue, in part thanks to Christian anarchist and pacifist Adin Ballou who spoke on the subject at the Concord Lyceum on occasion and who founded the New England Non-Resistance Society (of which William Lloyd Garrison was also a leader, and a Lyceum speaker as well). 

Book 8: Thoreau’s essay "Wild Apples" first appeared in the Atlantic Monthly in 1862. It begins with a history of the apple tree, chronicling its journey from Ancient Greece to America. The author compares the history of the apple to that of mankind, contemplating it with a tragic eye. He considered the idea of wildness not as sinful, but the source of creativity.