Although Dr. Martin Luther King, Jr. was more politically active, both he and Henry David Thoreau strongly supported the idea of civil disobedience. Thoreau and King shared the view that there was much injustice in society, that it had to be confronted and eliminated, and that it should be done through both non-violent resistance to that injustice and an appeal to the morality and conscience of all involved. The differences between them largely had to do with style and form of expression in words and action. Thoreau went to jail in protest against a tax which supported a system condoning slavery in his own state of Massachusetts, but certainly his political activism paled beside that of King, who dedicated (and lost) his life to a continuous struggle using civil disobedience to fight racial and socioeconomic injustice.
Thoreau was by far the more caustic in addressing these injustices and those who perpetuate them. King tried to address even the most vile bigot with some sense of dignity in the hope that the best in the bigot could be reached through such non-judgment. Thoreau never tried to conceal his contempt for not only the perpetrator of injustice but for every individual who tried to pursue selfish and material goals while others suffered from injustice around them:
The majority of the men ... are not men of principle. If they vote, they do not send men to Congress on errands of humanity; but while their brothers and sisters are being scourged and hung for loving liberty, ... it is the mismanagement of wood and iron and stone and gold which concerns them (Thoreau "Slavery").
Thoreau seemed to more address the individual than the collective, while King dealt more with society as a whole. King clearly depended on the decisions of the federal government to support his civil rights goals, while Thoreau seemed to put the burden almost exclusively on the individual. King's civil disobedience was meant to stir the consc...