Thoreau began his studies at Harvard College in 1833. His years at Harvard were stimulating, if solitary; he immersed himself in a traditional humanities curriculum of multiple languages, anatomy, history, and geography. Upon graduation in 1837, he began teaching in Concord at the Center School, the public school he'd attended as a boy, but left his post after being told to administer corporal punishment to a student. During these years following college Thoreau published his first essay and poem, began lecturing at the Concord Lyceum, and attended Transcendentalist discussions at the home of his mentor, the renowned essayist and poet Ralph Waldo Emerson. At Emerson's urging, Thoreau started a journal -- a project that would become his lifelong passion and culminate in more than two million words.

A boat trip with his brother, John, in 1839 set the foundation for his well known work A Week on the Concord and Merrimack Rivers. Sadly, unforeseen tragedy separated the tightly knit brothers in 1842, when John died of lockjaw caused by a razor cut. The following year, Thoreau joined Emerson in editing the Transcendental periodical The Dial, a publication to which Thoreau would become a prolific contributor. He also pulled up stakes for a time, accepting a position to tutor Emerson's children in Staten Island, New York. Half a year later, Thoreau returned to his family's house in Concord, deeply affected by the abolitionists he had met in Manhattan. He dedicated much of his time to lectures and essays advocating abolition and became involved in sheltering runaway slaves on their journey north.

In 1846 Thoreau was briefly imprisoned for refusing to pay a poll tax to the village of Concord, in protest against the government's support of slavery, as well as its war of expansion with Mexico. His experience in the Concord jail led to the writing of what would later be titled "Civil Disobedience." Unappreciated in Thoreau's lifetime, "Civil Disobedience" is now considered one of the country's seminal political works.

During this period, Thoreau built his cabin on Walden Pond and lived there for a little more than two years. In this small home on Emerson's property, he began writing his most enduring work, Walden; or, Life in the Woods, and finished the manuscript for A Week on the Concord and Merrimack Rivers. Sales were exceedingly poor, with Thoreau eventually acquiring 706 unsold copies of the original 1000 copy print run. Thoreau quipped, "I have now a library of nearly nine hundred volumes, over seven hundred of which I wrote myself." When Walden was published in 1854, sales were brisk and its reception favorable, although Thoreau's work as a whole remained somewhat obscure during his lifetime.

By the time Walden was published, Thoreau had turned from the largely symbolic approach to nature that he had learned from Emerson and other Romantic writers to a much more empirical approach, more in keeping with new scientific methods. His observations of nature throughout the 1850s, largely recorded in his journals, have come to be regarded as a model of ecological attentiveness, even though the term "ecology" was not coined until 1866. He developed several talks on the natural history of the Concord region, and even set to work on a series of longer, book-length manuscripts. Two of these, one on the dispersal of tree seeds and the other on the region's many wild fruits, were not published until 1993 and 2000 respectively. Today, Thoreau's writing is valued for both the poetic imagination and the scientific methodology it displays.

As the years passed, Thoreau's commitment to the antislavery movement strengthened, as did his popularity as a lecturer and essayist. Even in the declining health of his later years, he remained a man of conviction and action, writing on many subjects and participating in various political causes until shortly before his death from tuberculosis. George Eliot's review of Walden singles out qualities that attract readers to this day: "a deep poetic sensibility" and "a refined as well as a hardy mind." Henry David Thoreau died on May 6, 1862, in Concord.

Author biography from the Barnes & Noble Classics edition of Walden.