This is the text of an inaugural lecture delivered by Daniel Howe at the University of Oxford in May 1990, in which he argues that Thoreau's essay of 1849 commending the duty of civil disobedience is one of the most widely read American literary texts, invoked by Gandhi, Tolstoy, Martin Luther King and other protest leaders. The title "Civil Disobedience" is the creation of posthumous editors - Thoreau, who wrote the essay after spending a night in jail for non-payment of the poll tax in July 1846 as a protest against slavery and the Mexican War, called it "Resistance to Civil Government". Drawing upon a mixture of liberal, romantic, and Christian sources, he argues that 1) there is a duty to disobey immoral commands; 2) there is a right to break the laws of immoral governments; 3) social progress depends on the moral leadership of a courageous minority. He does not argue that civil resistants should accept legal punishment, nor does he repudiate violence. The text should interest students and scholars of American history and literature, and the history of civil disobedience.