Originally published in 1866, Civil Disobedience asks when—and in what circumstances—an individual should actively oppose government and its justice system. Thoreau's argument is that opposition is legitimate whenever government actions or institutions are unacceptable to an individual's conscience. But he goes further, saying anyone who believes something to be wrong has a duty to resist it actively. While he was not widely known during his lifetime, the ideas he put forward in Civil Disobedience became highly influential and inspired activists—including Martin Luther King Jr., Mahatma Gandhi, and Nelson Mandela—in peacefully opposing their own governments.