“I hold that the Federal Government was never, in its essence, anything but an anti-slavery government. Abolish slavery tomorrow, and not a sentence or syllable of the Constitution need be altered. It was purposely so framed as to give no claim, no sanction to the claim, of property in a man. If in its origin slavery had any relation to the government, it was only as the scaffolding to the magnificent structure, to be removed as soon as the building was completed.”

2000s, The Real Abraham Lincoln: A Debate (2002), Q&A

Source: Look Away!: A History of the Confederate States of America (2002), p. 3

2000s, The Real Abraham Lincoln: A Debate (2002), Q&A

1860s, The Constitution of the United States: Is It Pro-Slavery or Anti-Slavery? (1860)
Context: I, on the other hand, deny that the Constitution guarantees the right to hold property in man, and believe that the way to abolish slavery in America is to vote such men into power as well use their powers for the abolition of slavery. This is the issue plainly stated, and you shall judge between us.

The Supreme Court: How it Was, How it Is (1987).
Books, articles, and speeches
Context: An oft-heard description of the Supreme Court is that it is the ultimate protector in our society of the liberties of the individual. This phrase describes an important role of the Supreme Court, but by ignoring other equally important functions of the Court, it has a potential for mischief. It is a fairly short leap from this language to a feeling that the US Constitution is somehow "vindicated" every time a claim of individual right against government is upheld, and is not vindicated whenever such a claim is not upheld. But this, of course, cannot be the case. The role of the Supreme Court is to uphold those claims of individual liberty that it finds are well-founded in the Constitution, and to reject other claims against the government that it concludes are not well-founded. Its role is no more to exclusively uphold the claims of the individual than it is to exclusively uphold the claims of the government: It must hold the constitutional balance true between these claims.

1860s, Allow the humblest man an equal chance (1860)
Context: It is easy to demonstrate that "our Fathers, who framed this government under which we live," looked on Slavery as wrong, and so framed it and everything about it as to square with the idea that it was wrong, so far as the necessities arising from its existence permitted. In forming the Constitution they found the slave trade existing; capital invested in it; fields depending upon it for labor, and the whole system resting upon the importation of slave-labor. They therefore did not prohibit the slave trade at once, but they gave the power to prohibit it after twenty years. Why was this? What other foreign trade did they treat in that way? Would they have done this if they had not thought slavery wrong? Another thing was done by some of the same men who framed the Constitution, and afterwards adopted as their own act by the first Congress held under that Constitution, of which many of the framers were members; they prohibited the spread of Slavery into Territories. Thus the same men, the framers of the Constitution, cut off the supply and prohibited the spread of Slavery, and both acts show conclusively that they considered that the thing was wrong. If additional proof is wanting it can be found in the phraseology of the Constitution. When men are framing a supreme law and chart of government, to secure blessings and prosperity to untold generations yet to come, they use language as short and direct and plain as can be found, to express their meaning. In all matters but this of Slavery the framers of the Constitution used the very clearest, shortest, and most direct language. But the Constitution alludes to Slavery three times without mentioning it once! The language used becomes ambiguous, roundabout, and mystical. They speak of the "immigration of persons," and mean the importation of slaves, but do not say so. In establishing a basis of representation they say "all other persons," when they mean to say slaves — why did they not use the shortest phrase? In providing for the return of fugitives they say "persons held to service or labor." If they had said slaves it would have been plainer, and less liable to misconstruction. Why didn't they do it. We cannot doubt that it was done on purpose. Only one reason is possible, and that is supplied us by one of the framers of the Constitution — and it is not possible for man to conceive of any other — they expected and desired that the system would come to an end, and meant that when it did, the Constitution should not show that there ever had been a slave in this good free country of ours!

(1847)

Source: Political Aphorisms, Moral and Philosophical Thoughts (1848), p. 246

"The Address of the Southern and Western Liberty Convention" http://alexpeak.com/twr/libertyparty/saw/, in Anti-slavery Addresses of 1844 and 1845 by Salmon Portland Chase and Charles Dexter Cleveland, ed. C. D. C. (London: Sampson Low, Son, and Martson, 1867), pp. 75–125.