“The movement of the middle classes for the abolition of slavery was virtuous, but it was not wise. It was an ignorant movement. It showed a want of knowledge both of the laws of commerce and the stipulations of treaties; and it has alike ruined the colonies and aggravated the slave trade…The history of the abolition of slavery by the English and its consequences, would be a narrative of ignorance, injustice, blundering, waste, and havoc, not easily paralleled in the history of mankind.”

"A View of the Causes and Consequences of the American Revolution" (London, Robinson, 1797)

A Summary View of the Rights of British America http://alexpeak.com/twr/jefferson/#1784 (July 1774)
1770s
Context: For the most trifling reasons, and sometimes for no conceivable reason at all, his majesty has rejected laws of the most salutary tendency. The abolition of domestic slavery is the great object of desire in those colonies where it was unhappily introduced in their infant state. But previous to the infranchisement of the slaves we have, it is necessary to exclude all further importations from Africa. Yet our repeated attempts to effect this by prohibitions, and by imposing duties which might amount to a prohibition, have been hitherto defeated by his majesty’s negative: thus preferring the immediate advantages of a few British corsairs to the lasting interests of the American states, and to the rights of human nature deeply wounded by this infamous practice.

2000s, God Bless America (2008), Slavery and the Human Story
Context: But one may ask, how is it that slavery, or any other form of invidious discrimination, has played so great a role in American history? How could a nation, dedicated at its birth to the proposition that all men are created equal, have tolerated slavery and its effects so long? If we look to the long history of mankind, however, we will ask a different question. Slavery was lawful in every one of the original thirteen states. There was accordingly nothing remarkable in the fact that slavery was not abolished immediately on independence. What is remarkable is that a slave-owning nation would declare that all men are created equal, and thereby make the abolition of slavery a moral and political necessity. To accomplish that task would not be easy. We need to see the dimensions of that task to appreciate its difficulty.

Source: Miles: The Autobiography

Source: Pakistan or The Partition of India (1946), p. 228

Documentary films, America: Imagine the World Without Her (2014)

Source: In Praise of Philosophy (1963), p. 5
Context: Even those who have desired to work out a completely positive philosophy have been philosophers only to the extent that, at the same time, they have refused the right to install themselves in absolute knowledge. They taught not this knowledge, but its becoming in us, not the absolute but, at most, our absolute relation to it, as Kierkegaard said. What makes a philosopher is the movement which leads back without ceasing from knowledge to ignorance, from ignorance to knowledge, and a kind of rest in this movement.

1850s, The Present Aspect of the Slavery Question (1859)

John Brown and the Principle of Nonresistance http://teachingamericanhistory.org/library/index.asp?document=569 (16 December 1859)
Context: We have a natural right, therefore, to seek the abolition of slavery throughout the globe. It is our special duty to make Massachusetts free soil, so that the moment the fugitive slave stands upon it, he shall take his place in the ranks of the free. God commands us to "hide the outcast, and bewray not him that wandereth." I say, LET THE WILL OF GOD BE DONE! That is "the head and front" of my "fanaticism"! That is the extent of my "infidelity"! That comprehends all of my "treason"! THE WILL OF GOD BE DONE!