Main idea that best summarizes the text "Civil Disobedience"

During his stay at Walden Pond (later to become the subject of his published journal Walden, or Life in the Woods), Thoreau spent one night in jail for refusing to pay a poll tax meant to support America's war with Mexico. He composed a letter from jail that he would later integrate into Civil Disobedience, published in 1849 under the title Resistance to Civil Government. (It is interesting to note that the term "civil disobedience" does not appear in the actual essay.) Thoreau's incarceration brought him firsthand knowledge of the coercive and oppressive tactics used by government to compel its citizens into support of immoral and unjust policies. But it also highlighted the importance of individual moral conscience. The experience became the point of departure for Thoreau's much broader reflection on the duty of civil disobedience.