Henry David Thoreau perhaps is best known for Walden, or Life in the Woods (1854), the product of a two-year stay in a handmade cabin on the shore of Walden Pond just outside of rural Concord, Massachusetts. He compressed his memories and observations in the mid-1840s into a book a single calendar year long.

Though the book initially inspired little fanfare, critics of a different era regard the work as a classic. In the work, Thoreau uses the four seasons to symbolize human development, and to explore Nature’s simplicity, beauty, and harmony as models for social and cultural justice.

Thoreau also wrote On the Duty of Civil Disobedience (1849), after a night in the local jail, in which he criticized centralized government and argued that the individual should resist the state if it required him to “be an agent of injustice to another [human being]." Thoreau had been arrested for his refusal to pay a poll tax to support the Mexican-American War.

David Henry, as he was known until after his Harvard years, was born in Concord, Massachusetts, in 1817. He came of age in the flourishing years of some of the greatest American writers — Ralph Waldo Emerson, Nathaniel Hawthorne, and Herman Melville, to name just three whom he met.

Following graduation from Harvard in 1837, Thoreau took a number of small-time jobs, so he could eat every so often. He taught school, did some surveying, made pencils, and tutored some. In 1837, Emerson persuaded Thoreau to keep a journal of observations, and later saw fit to publish some of them as essays in his Transcendentalist paper, The Dial. Assuming a patriarch/mentor role, Emerson also persuaded Thoreau to reside with him in 1841.

Beginning July 4, 1845, Thoreau spent two years, two months, and two days in relative isolation, broken only by trips to the cabin by Emerson to provide daily necessities. Thoreau also made the occasional excursion into Concord. On one trip, he had the dubious pleasure of bumping into the local tax collector; hence, the poll tax issue.

Thoreau’s fascination with botany and natural history increased exponentially with the discovery of the works of William Bartram and, especially, Charles Darwin’s Voyage of the Beagle. In his journals, Thoreau noted migrating birds; the interaction among species, places, and seasons; and the life cycle of forests.

He also left his cabin to hike the Mount Katahdin wilderness in Maine, which led to an essay titled Ktaadn. Thoreau made several more trips to the Pine Tree state over 11 years. Those woodsy treks culminated in two more essays, Chesuncook, and Allegash & East Branch. The essays were compiled in a book, The Maine Woods.

His Excursions marks Thoreau as one of the earliest American environmentalists. The essays contained therein cover such subjects as the dispersal of seeds and the autumnal foliage of New England. He was an early advocate of outdoor recreation, including canoeing and hiking, and of preserving the wilderness as public land.

Although Thoreau had contracted tuberculosis in 1835 — no doubt abetted by his stint in the family pencil factory — he remained reasonably robust until he slogged through a rain storm to count the rings on a tree stump in 1859.

Thoreau seemed to grasp the gravity of his situation and increased the pace at which he wrote his works. Bedridden during the final months, he continued to dictate to his sister.