Civil Disobedience (Resistance to Civil Government) is an essay by Henry David Thoreau that was first published in 1849. It argues that people should not permit governments to overrule or atrophy their consciences, and that people have a duty to avoid allowing such acquiescence to enable the government to make them the agents of injustice.
Resistance also served as part of Thoreau's metaphor comparing the government to a machine: when the machine was producing injustice, it was the duty of conscientious citizens to be "a counter friction" (i.e., a resistance) "to stop the machine".
The word civil has several definitions. The one that is intended in this case is "relating to citizens and their interrelations with one another or with the state", and so civil disobedience means "disobedience to the state.
Thoreau asserts that because governments are typically more harmful than helpful, they therefore cannot be justified. Democracy is no cure for this, as majorities simply by virtue of being majorities do not also gain the virtues of wisdom and justice. The judgment of an individual's conscience is not necessarily inferior to the decisions of a political body or majority, and so "[i]t is not desirable to cultivate a respect for the law, so much as for the right. The only obligation which I have a right to assume is to do at any time what I think right... Law never made men a whit more just; and, by means of their respect for it, even the well-disposed are daily made the agents of injustice.
"That government is best which governs least" ~ Henry David Thoreau