“Men being, as has been said, by nature, all free, equal and independent, no one can be put out of this estate, and subjected to the political power of another, without his own consent.”

Second Treatise of Government, Ch. IX, sec. 123
Two Treatises of Government (1689)

Remarks on Annual Elections (1775)

De concordantia catholica (The Catholic Concordance) (1434)

2000s, The Logic of the Colorblind Constitution (2004)
Context: Harlan's dissenting opinion in Plessy, that the Constitution was colorblind, and that it did not countenance different and unequal classes of citizens, was based upon a belief in the truth of the principle of equality in which the founders and Lincoln had so profoundly believed. But this belief had been buried by progressivism, and has not been resurrected, except by the intellectual heirs of Leo Strauss. On intellectual grounds, it has never been refuted, and ought never to have been abandoned. There is not now, and never has been any such difference between one human being and another human being, or whatever race or color, such that one is by nature the ruler of the other, as any human being is by nature the ruler of any dog or any horse. For this reason, legitimate political authority can arise only by the consent of the governed, and consent can never be given for any reason other than the equal protection of the rights of the governed. Hence equal protection is the foundation of all constitutionalism, even apart from its specific inclusion in the Constitution itself. For more reasons than one, Justice Harlan's dissenting opinion ought to have been the opinion of the Court in 1896; even more ought it to have been the opinion of the Court in 1954. As Professor Edward J. Erler has demonstrated in the pages of the Claremont Review of Books, the principle of equal protection has never become the opinion of the Supreme Court of the United States, nor has it been favored in the writings of conservative jurists.

Two Treatises of Government (1689)
Source: Second Treatise of Government, Ch. II, sec. 6
Context: The state of nature has a law of nature to govern it, which obliges every one: and reason, which is that law, teaches all mankind, who will but consult it, that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions.

2000s, The Central Idea (2006)
Context: The equality of mankind is best understood in light of a two-fold inequality. The first is the inequality of mankind and of the subhuman classes of living beings that comprise the order of nature. Dogs and horses, for example, are naturally subservient to human beings. But no human being is naturally subservient to another human being. No human being has a right to rule another without the other's consent. The second is the inequality of man and God. As God's creatures, we owe unconditional obedience to His will. By that very fact however we do not owe such obedience to anyone else. Legitimate political authority—the right of one human being to require obedience of another human being—arises only from consent. The fundamental act of consent is, as the 1780 Massachusetts Bill of Rights states, "a social compact by which the whole people covenants with each citizen and each citizen with the whole people that all shall be governed by certain laws for the common good." The "certain laws for the common good" have no other purpose but to preserve and protect the rights that each citizen possesses prior to government, rights with which he or she has been "endowed by their Creator." The rights that governments exist to secure are not the gift of government. They originate in God.

The Educational Theory of Immanuel Kant (1904)
Context: Man has his own inclinations and a natural will which, in his actions, by means of his free choice, he follows and directs. There can be nothing more dreadful than that the actions of one man should be subject to the will of another; hence no abhorrence can be more natural than that which a man has for slavery. And it is for this reason that a child cries and becomes embittered when he must do what others wish, when no one has taken the trouble to make it agreeable to him. He wants to be a man soon, so that he can do as he himself likes.

Part III : Selection on Education from Kant's other Writings, Ch. I Pedagogical Fragments, # 62

2000s, Before In History (2004)

Here was the doctrine of equality, popular sovereignty, and the substance of the theory of inalienable rights clearly asserted by Wise at the opening of the eighteenth century, just as we have the principle of the consent of the governed stated by Hooker as early as 1638.
1920s, Speech on the Anniversary of the Declaration of Independence (1926)