Henry is a 29-year-old philosopher, naturalist, and fierce individualist living in Concord, Massachusetts. He holds uncompromising principles regarding personal liberty and actively rejects society's materialism. His decision to refuse to pay a poll tax—a protest against the government's funding of the Mexican American War—lands him in jail, where he reflects on his past choices.

Waldo is a prominent thinker, lecturer, and the founder of American Transcendentalism. He travels widely to speak about self-reliance and the divine nature of the individual. Though his ideas inspire Henry, Waldo prefers to operate within the bounds of society, enjoying the comforts of his status and home.

John is Henry's older brother by two years. He possesses a gentle, moderate disposition that often serves to soften Henry's rigid principles. Together, the brothers attempt to open an experimental school that encourages students to learn through outdoor exploration rather than rote memorization.

Lydian is Waldo's intelligent wife. She manages the Emerson household and cares for their son while her husband travels the lecture circuit. She recognizes the impracticality of Henry's extreme nonconformity but maintains a sympathetic connection to him, often worrying about his loneliness.

Bailey is an illiterate vagrant who shares Henry's jail cell. He has been locked up for three months awaiting trial on arson charges. Unlike Henry, Bailey actively wishes to avoid trouble and just wants to get along with the authorities, preferring a quiet and unbothered life.

Williams is a Black man escaping enslavement in the South, attempting to make his way to safety in Canada. He is exhausted and frightened when he first encounters Henry. Treated with basic human dignity, he briefly considers staying in Massachusetts before realizing the danger of his situation persists.

Sam is the local constable in Concord. He genuinely respects Henry and feels reluctant to arrest him, going so far as to offer to pay the poll tax out of his own pocket. However, he ultimately performs his duty as an officer of the law.

Deacon Ball is the Chairman of the Concord School Committee. He strictly enforces traditional education, demanding that teachers rely entirely on approved textbooks and maintain order through strict corporal punishment.

Ellen is a twenty-year-old woman whose younger brother attends John and Henry's experimental outdoor school. She is curious about transcendentalism but struggles to fully understand Henry's intense philosophical explanations.

Edward is the young son of Waldo and Lydian Emerson. He spends significant time with Henry while his father is away on lecture tours. He joins the young philosopher on huckleberry-picking excursions and develops a strong attachment to him.