When Lincoln spoke at the Cooper Union for the Advancement of Science and Art in New York City, he had not yet secured the Republican presidential nomination. Speaking to a skeptical eastern audience for the first time, Lincoln made a historically informed and legally learned case for the Republican view that in drafting the Constitution the Founders had not intended to protect the institution of slavery in perpetuity, but looked forward to its demise. In adhering to the original intention of the Founders, the Republican Party was – contrary to its critics’ charges of sectionalism, radicalism, and revolt – the truly national and conservative party devoted to conserving the Union. Lincoln’s hugely successful speech was instrumental in securing his nomination for the presidency.

Mr. President and Fellow-Citizens of New York:

The facts with which I shall deal this evening are mainly old and familiar; nor is there anything new in the general use I shall make of them. If there shall be any novelty, it will be in the mode of presenting the facts, and the inferences and observations following that presentation.

In his speech last autumn, at Columbus, Ohio, as reported in The New York Times, Senator Douglas said:

I fully indorse this, and I adopt it as a text for this discourse. I so adopt it because it furnishes a precise and an agreed starting point for a discussion between Republicans and that wing of the Democracy headed by Senator Douglas. It simply leaves the inquiry: “What was the understanding those fathers had of the question mentioned?”

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