[S]laves are never referred to in the Constitution as anything but 'persons', a characterization that is perfectly neutral as to race or sex. That so… - Harry V. Jaffa

The issue between Lincoln and Douglas was identical to the issue between Socrates and Thrasymachus in the first book of Plato's Republic. Not similar to it. Identical. It is a question of whether the people make the moral order or the moral order makes the people.

In 1896, in Plessy v. Ferguson, the Court decided that 'separate but equal' did not violate the equal protection clause, and the South and not only the South relied upon this decision in building their systems of racially segregated public schools. The Court's 1896 decision can be explained in part by reason of the fact that the country—and the Western World generally—was then nearly submerged by the 'evolutionary' enlightenment. This movement, which dominated the intellectual elites in the universities, the law schools, and the media, denied the story of Creation in the Bible, and rejected the hitherto received idea that "God hath made of one blood all nations of men for to dwell on all the face of the earth." It entertained instead the idea that the races of mankind did not all emerge at the same time from the subhumanity which preceded their humanity. Evolutionary doctrine encouraged the idea that there was a fundamental inequality among the aforesaid races, and this idea virtually relegated to the "dustbin of history" the contrary idea, enshrined in the Declaration of Independence and the Gettysburg Address, "that all men are created equal."

And Lincoln in his Cooper Union speech, which he gave in February of 1860, raised the question, 'What can we do to satisfy our Southern brethren? No assurances that we give them that we will have no intention of interfering with the institution of slavery where it exists will satisfy them. We must get rid of all anti-slavery sentiments from our state constitutions'.