Henry David Thoreau was, in fact, born David Henry Thoreau on July 12^th, 1817 on Virginia Road in Concord, Massachusetts.  His parents were John Thoreau, a pencil maker, and Cynthia Dunbar. 

He was originally named in tribute to a recently deceased paternal uncle, David Thoreau.  Only after graduating from Harvard did his name become the more familiar Henry David.  He was one of four children; the older Helen and John Jr, and a younger sister, Sophia. 

John Thoreau suffered business difficulties causing the family to move several times, from Concord to Chelmsford, Massachusetts in 1818, and from there back to Concord for a few months in 1821, before on to Boston in 1821, and finally back to Concord permanently in 1823. 

After returning to Concord, John Thoreau rented a succession of houses before he could afford to build a home of his own on Texas Street in 1844. In 1849, John Thoreau bought and renovated a larger home on Main Street (the "Yellow House"), to which the family moved in 1850. 

Although the Thoreau’s were by no means even financially comfortable they strove to enrol Henry at Harvard. His older siblings even contributing some of their own earnings as teachers for the cause.  They were by all indications a close knit and loving family. 

Henry studied at Harvard between 1833 and 1837 taking classes in rhetoric, classics, philosophy, mathematics, and science. He was also a member of the Institute of 1770 (now the Hasty Pudding Club). 

The more usual professions open to college graduates—law, the church, business, medicine—all failed to elicit any interest in Thoreau. 

In 1835 during a leave of absence from Harvard, he taught school in Canton, Massachusetts. That same year he also contracted tuberculosis and was to suffer occasional bouts for the rest of his life. 

Thoreau graduated in 1837. A story persists that Thoreau refused to pay a five dollar fee for a Harvard diploma. In fact, the master's degree had no academic merit: Harvard College offered it to graduates "who proved their physical worth by being alive three years after graduating, and their saving, earning, or inheriting quality or condition by having Five Dollars to give the college." Thoreau’s retort was: "Let every sheep keep its own skin", a reference to diplomas being written on sheepskin vellum. 

He gained employment at the faculty of the Concord public school, but resigned within weeks rather than administer corporal punishment, a principle he would adhere to throughout his life. 

Thoreau now decided to bring more progressive educational ideas to schooling. Together with his brother John he opened a grammar school, initially it was based in the family home but later moved to the Concord Academy building, which Thoreau rented when the Academy lost its schoolmaster. Thoreau eventually took over the name as well as the building. 

The school was open to boarding and day students, the boarding students staying in the nearby Thoreau family home.  Most of the pupils were from Concord and its surrounds. A few from farther away. The curriculum included English, Latin, Greek, French, mathematics, physics, and natural history together with walks and visits to local shops and businesses. The education was very much “hands on”. 

The brothers also dispensed with physical punishment. Successful though the school was, it closed in 1841 when John became fatally ill from tetanus after cutting himself shaving. He died in his brothers’ arms. 

In Concord, Thoreau met the esteemed poet Ralph Waldo Emerson. Emerson took a fatherly interest in Thoreau, advising him and introducing him to a local circle of writers, among them Nathaniel Hawthorne and his young son, Julian Hawthorne. 

In 1839, Henry and John Thoreau made a boat trip down the Concord river and then along the Merrimack as far as Hooksett, New Hampshire, before continuing on land to Concord and Plymouth, New Hampshire. This journey was the raw material for Thoreau's published work, A Week on the Concord and Merrimack Rivers (eventually published in 1849). 

During this period both brothers also fell in love with the same girl, Ellen Sewall of Scituate, the older sister of their pupil Edmund Sewall. Both proposed marriage — John in July of 1840, Henry later that year. Neither proposal was accepted. 

At Emerson’s urging Thoreau began to write essays and was soon sending them to the editor of the quarterly periodical, The Dial. His first published essay was on Aulus Persius Flaccus, a playwright, in July 1840. The essay consisted of reworked passages from his journal which he had begun to keep from 1837. The first entry, dated October 22^nd, reads, "'What are you doing now?' he asked. 'Do you keep a journal?' So I make my first entry to-day." 

Thoreau was a philosopher of nature and how it affected the human condition. In his early years he also followed Transcendentalism, an eclectic, idealist philosophy advocated by Emerson, and others writers including Fuller, and Alcott. It was to also became a small, but note-worthy, poetry movement. 

The central tenet was that an ideal spiritual state transcends the physical and empirical, and that this insight is achieved not by religious doctrine but by personal intuition. In their view, Nature is the outward sign of inward spirit. Or, as Emerson expressed it, the "radical correspondence of visible things and human thoughts". 

On April 18^th, 1841, Thoreau moved into the Emerson house and, until 1844, he had a number of tasks; serving as the children's tutor, editorial assistant, repair man and gardener. 

For a few months in 1843 he moved into the home of William Emerson on Staten Island.  Here he tutored the family sons while also seeking contacts among the literary men and journalists in the city who might help publish his writings, including his future literary representative Horace Greeley. 

Thoreau returned to Concord and worked in his family's pencil factory, a job he continued to do for most of his adult life when time allowed. He rediscovered the process to mix inferior graphite and still, using clay as the binder, produce a good pencil.  Later, Thoreau later converted the factory to produce plumbago (graphite), which was used to ink typesetting machines. 

It was during this time in April 1844 that together with his friend, Edward Hoar, they accidentally set fire to part of Walden Woods, eventually destroying some 300 acres. 

Thoreau was deeply influenced by Nature and especially the Walden woods. As he said “I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived. I did not wish to live what was not life, living is so dear; nor did I wish to practise resignation, unless it was quite necessary. I wanted to live deep and suck out all the marrow of life, to live so sturdily and Spartan-like as to put to rout all that was not life, to cut a broad swath and shave close, to drive life into a corner, and reduce it to its lowest terms, and, if it proved to be mean, why then to get the whole and genuine meanness of it, and publish its meanness to the world; or if it were sublime, to know it by experience, and be able to give a true account of it in my next excursion”. 

Writing was constantly in his mind but he would need to work rather harder to convert his experiences into writing.   Though his journal entries continued the books for which his fame would endure were still not yet published.  

In March 1845, Ellery Channing told Thoreau, "Go out upon that, build yourself a hut, & there begin the grand process of devouring yourself alive. I see no other alternative, no other hope for you." 

Within months Thoreau had decided on a radical two year experiment in simple living. It began, ironically on July 4^th, 1845; Independence Day, with a move to a small, self-built house on fourteen acres of land owned by Emerson on the shores of Walden Pond. The house was in "a pretty pasture and woodlot." 

In late July of the following year Thoreau ran into the local tax collector, Sam Staples, who requested that he pay his delinquent poll taxes going back six years. Thoreau refused because of his opposition to the Mexican-American War and slavery. He spent the night in jail. His opposition to the war did not stem from pacifism, but because he considered Mexico "unjustly overrun and conquered by a foreign army" as a means to expand the slave territory. 

The next day Thoreau was freed when a benefactor, paid the tax against his wishes. The experience had a strong impact on him. In January and February 1848, he delivered lectures on "The Rights and Duties of the Individual in relation to Government" explaining his tax resistance at the Concord Lyceum. The writer Bronson Alcott attended the lecture, writing in his journal on January 26 – “Heard Thoreau's lecture before the Lyceum on the relation of the individual to the State – an admirable statement of the rights of the individual to self-government, and an attentive audience. His allusions to the Mexican War, to Mr. Hoar's expulsion from Carolina, his own imprisonment in Concord Jail for refusal to pay his tax, Mr. Hoar's payment of mine when taken to prison for a similar refusal, were all pertinent, well considered, and reasoned. I took great pleasure in this deed of Thoreau's”. 

Thoreau would revise the lecture into an essay entitled Resistance to Civil Government (and better known as On the Duty of Civil Disobedience). 

In May 1849 it was published by Elizabeth Peabody in the Aesthetic Papers. 

At Walden Pond, he completed a first draft of A Week on the Concord and Merrimack Rivers, an elegy to his brother, John, that described their earlier 1839 trip to the White Mountains.

 Unfortunately, a publisher could not be found and so Thoreau printed a 1000 copies at his own expense. It sold little, perhaps 300 copies. 

In August 1846, Thoreau briefly left Walden to make a trip to Mount Katahdin in Maine, a journey later recorded in "Ktaadn", the first part of The Maine Woods. 

Thoreau left Walden Pond on September 6^th, 1847. At Emerson's request, he immediately moved back into the Emerson house to help his wife, Lidian, manage the household while he was on a trip to Europe. 

Over several years, he worked to pay off his debts and also constantly revised his manuscript for what, in 1854, he would publish as Walden, or Life in the Woods, recounting the two years, two months, and two days he had spent at Walden Pond. The finished book compressed that time into a single twelve months, using the passage of the seasons to symbolize human development. Part memoir and part spiritual quest, Walden at first won few admirers, but it is now regarded as an American classic. 

Thoreau moved out of Emerson's house in July 1848 and stayed at nearby Belknap street before moving with the Thoreau family into their new house in 1850 at 255 Main Street; he stayed there until his death. 

In 1851, Thoreau became increasingly fascinated with natural history and narratives on travel and expedition. He read avidly on botany and often wrote on the subject in his journal. He admired William Bartram, and Charles Darwin's Voyage of the Beagle. He kept detailed observations on Concord's nature lore, recording everything from how the fruit ripened over time to the fluctuating depths of Walden Pond and on which days certain birds migrated. His aim was to "anticipate" the seasons of nature. 

He became a land surveyor and continued to write increasingly detailed natural history observations about his surroundings in his journal, which over twenty four years, became a two million word document. He also kept a series of notebooks, and these observations became the source for Thoreau's later natural history writings, such as Autumnal Tints, The Succession of Trees, and Wild Apples, an essay lamenting the destruction of indigenous and wild apple species. 

He travelled to Quebec once, Cape Cod four times, and Maine three times; the landscapes he walked through inspired his "excursion" books; A Yankee in Canada, Cape Cod, and The Maine Woods, in which travel itineraries frame his thoughts about geography, history and philosophy. 

At other times his travels took him southwest to Philadelphia and New York City in 1854, and west across the Great Lakes region in 1861, visiting Niagara Falls, Detroit, Chicago, Milwaukee, St. Paul and Mackinac Island. 

Although provincial in his physical travels, he was extraordinarily well-read. He obsessively devoured all the first-hand travel accounts available.  It was an exciting time; the last unmapped regions of the earth were being explored. He read Magellan and James Cook, the arctic explorers Franklin, Mackenzie and Parry, David Livingstone, Richard Francis Burton, Lewis and Clark; and many other lesser-known works by explorers and literary travellers.  Everything so consumed fed his appetite for more knowledge on peoples, cultures, religions and the natural history of the world, and left its traces and knowledge as commentaries in his lengthy journals and other volumes of work. 

Despite his wish to live simply and at peace with Nature several issues could ignite him. One such was slavery. He was a fierce and vocal Abolitionist.  After John Brown's raid on Harpers Ferry, many prominent voices in the abolitionist movement distanced themselves from Brown, or damned him with faint praise. Thoreau was disgusted by this, and he composed a speech — A Plea for Captain John Brown — which was uncompromising in its defence of Brown and his actions. Thoreau's speech proved persuasive: first the abolitionist movement began to accept Brown as a martyr, and by the time of the American Civil War entire armies of the North were singing Brown's praises. A biographer of John Brown said: "If, as Alfred Kazin suggests, without John Brown there would have been no Civil War, we would add that without the Concord Transcendentalists, John Brown would have had little cultural impact." 

Thoreau went so far as to compare the American government to Pontius Pilate and likened Brown's execution to the crucifixion of Jesus Christ: "Some eighteen hundred years ago Christ was crucified; this morning, perchance, Captain Brown was hung. These are the two ends of a chain which is not without its links. He is not Old Brown any longer; he is an angel of light." 

In The Last Days of John Brown, Thoreau described the words and deeds of John Brown as noble and an example of heroism. 

In 1859, following a late-night excursion to count the rings of tree stumps during a rain storm, he fell ill with bronchitis. His health now fell into an irreversible decline with only short periods of remission. 

Eventually he became bedridden. Knowing the terminal nature of his disease, Thoreau spent his last years revising and editing his unpublished works, particularly The Maine Woods and Excursions, and petitioning publishers to print revised editions of A Week and Walden. He wrote until he became too weak to continue. 

His friends were alarmed at his diminished appearance but equally fascinated by his graceful acceptance of death. When his aunt Louisa asked him in his last weeks if he had made his peace with God, Thoreau responded: "I did not know we had ever quarreled." 

Aware he was dying, Thoreau's last words were "Now comes good sailing", followed by two lone words, "moose" and "Indian". 

Henry David Thoreau died at his parent’s house on Main Street ‘the Yellow House’ on May 6^th, 1862 at the early age of age 44. 

Bronson Alcott planned the service and read selections from Thoreau's works, and Channing presented a hymn. 

Emerson wrote the eulogy spoken at his funeral. 

Originally buried in the Dunbar family plot, he and members of his immediate family were eventually moved to Sleepy Hollow Cemetery in Concord, Massachusetts.