“On the other hand, the free states carry on their government on the principle of the equality of men. We think slavery is morally wrong, and a direct violation of that principle. We all think it wrong. It is clearly proved, I think, by natural theology, apart from revelation. Every man, black, white or yellow, has a mouth to be fed and two hands with which to feed it, and that bread should be allowed to go to that mouth without controversy.”

Justice Thomas to Diane Brady, 2007. http://www.businessweek.com/articles/2013-01-15/clarence-thomas-brilliantly-breaks-his-silent-streak
2000s

Source: A Fatal Grace

A statement in this passage is sometimes paraphrased: "Men are better than their theology."
1840s, Essays: First Series (1841), Compensation
Context: I think that our popular theology has gained in decorum, and not in principle, over the superstitions it has displaced. But men are better than this theology. Their daily life gives it the lie. Every ingenuous and aspiring soul leaves the doctrine behind him in his own experience; and all men feel sometimes the falsehood which they cannot demonstrate. For men are wiser than they know. That which they hear in schools and pulpits without after-thought, if said in conversation, would probably be questioned in silence. If a man dogmatize in a mixed company on Providence and the divine laws, he is answered by a silence which conveys well enough to an observer the dissatisfaction of the hearer, but his incapacity to make his own statement.

Auditioning for the Apocalypse (1984)

1910s, Address to the Knights of Columbus (1915)
Context: Our nation was founded to perpetuate democratic principles. These principles are that each man is to be treated on his worth as a man without regard to the land from which his forefathers came and without regard to the creed which he professes. If the United States proves false to these principles of civil and religious liberty, it will have inflicted the greatest blow on the system of free popular government that has ever been inflicted. Here we have had a virgin continent on which to try the experiment of making out of divers race stocks a new nation and of treating all the citizens of that nation in such a fashion as to preserve them equality of opportunity in industrial, civil, and political life. Our duty is to secure each man against any injustice by his fellows.

Source: An Introduction to the Principles of Morals and Legislation (1789; 1823), Ch. 1 : Of the Principle of Utility

1860s, Letter to Alexander H. Stephens (1860)
Context: The South would be in no more danger in this respect than it was in the days of Washington. I suppose, however, this does not meet the case. You think slavery is right and should be extended; while we think slavery is wrong and ought to be restricted. That I suppose is the rub. It certainly is the only substantial difference between us.

Man a Machine (1747)

1860s, Allow the humblest man an equal chance (1860)
Context: Slavery is wrong. If Slavery is right, all words, acts, laws, and Constitutions against it, are themselves wrong, and should be silenced, and swept away. If it is right, we cannot justly object to its nationality — its universality; if it is wrong they cannot justly insist upon its extension — its enlargement. All they ask, we could readily grant, if we thought Slavery right; all we ask, they could as readily grant, if they thought it wrong. Their thinking it right, and our thinking it wrong, is the precise fact upon which depends the whole controversy. Thinking it right as they do, they are not to blame for desiring its full recognition, as being right; but, thinking it wrong, as we do, can we yield to them? Can we cast our votes with their view, and against our own? In view of our moral, social, and political responsibilities, can we do this?
Wrong as we think Slavery is, we can yet afford to let it alone where it is, because that much is due to the necessity arising from its actual presence in the nation; but can we, while our votes will prevent it, allow it to spread into the National Territories, and to overrun us here in these Free States?
If our sense of duty forbids this, then let us stand by our duty, fearlessly and effectively. Let us be diverted by none of those sophistical contrivances wherewith we are so industriously plied and belabored — contrivances such as groping for middle ground between the right and the wrong, vain as the search for a man who should be neither a living man nor a dead man — such as a policy of "don't care" on a question about which all true men do care — such as Union appeals beseeching true Union men to yield to Disunionists, reversing the divine rule, and calling, not the sinners, but the righteous to repentance — such as invocations of Washington, imploring men to unsay what Washington did.