Lincoln, however, remained under the impression that the lecture was to be given in Brooklyn, and only learned after he reached New York to fulfill his engagement that he was to speak in the Cooper Institute. When, on the evening of February 27, 1860, he stood before his audience, he saw not only a well-filled house, but an assemblage of listeners in which were many whom, by reason of his own modest estimate of himself, he would have been rather inclined to ask advice from than to offer instruction to. William Cullen Bryant presided over the meeting; David Dudley Field escorted the speaker to the platform; ex-Governor John A. King, Horace Greeley, James W. Nye, James A. Briggs, Cephas Brainerd, Charles C. Nott, Hiram Barney, and others sat among the invited guests. "Since the days of Clay and Webster," said the "Tribune" next morning, "no man has spoken to a larger assemblage of the intellect and mental culture of our city." Of course the presence of such a gathering was no mere accident. Not only had Lincoln's name for nearly two years found constant mention in the newspapers, but both friendly and hostile comment had coupled it with the two ranking political leaders in the free-States—Seward and Douglas. The representative men of New York were naturally eager to see and hear one who, by whatever force of eloquence or argument, had attracted so large a share of the public attention. We may also fairly infer that, on his part, Lincoln was no less curious to test the effect of his words on an audience more learned and critical than those collected in the open-air meetings of his Western campaigns. This mutual interest was an evident advantage to both; it secured a close attention from the house, and insured deliberation and emphasis by the speaker, enabling him to develop his argument with perfect precision and unity, reaching perhaps the happiest general effect ever attained in any one of his long addresses.

He took as his text a phrase uttered by Senator Douglas in the late Ohio campaign—"Our fathers, when they framed the government under which we live, understood this question just as well, and even better than we do now." Lincoln defined "this question," with a lawyer's exactness, thus:

Does the proper division of local from Federal authority, or anything in the Constitution, forbid our Federal Government to control as to slavery in our Federal Territories? Upon this Senator Douglas holds the affirmative, and the Republicans the negative. This affirmation and denial form an issue, and this issue—this question—is precisely what the text declares our fathers understood "better than we."

From this "precise and agreed starting-point" Lincoln next traced with minute historical analysis the action of "our fathers" in framing "the government under which we live," by their votes and declarations in the Congresses which preceded the Constitution and in the Congresses following which proposed its twelve amendments and enacted various Territorial prohibitions. His conclusions were irresistibly convincing.

The sum of the whole is [said he] that of our thirty-nine fathers who framed the original Constitution, twenty-one—a clear majority of the whole—certainly understood that no proper division of local from Federal authority, nor any part of the Constitution, forbade the Federal Government to control as to slavery in the Federal Territories; while all the rest probably had the same understanding. Such unquestionably was the understanding of our fathers who framed the original Constitution; and the text affirms that they understood the question "better than we".... It is surely safe to assume that the thirty-nine framers of the original Constitution and the seventy-six members of the Congress which framed the amendments thereto, taken together, do certainly include those who may be fairly called "our fathers who framed the Government under which we live." And so assuming, I defy any man to show that any one of them ever, in his whole life, declared that in his understanding any proper division of local from Federal authority, or any part of the Constitution, forbade the Federal Government to control as to slavery in the Federal Territories. I go a step further. I defy any one to show that any living man in the whole world ever did, prior to the beginning of the present century (and I might almost say prior to the beginning of the last half of the present century), declare that in his understanding any proper division of local from Federal authority, or any part of the Constitution, forbade the Federal Government to control as to slavery in the Federal Territories. To those who now so declare, I give, not only "our fathers who framed the government under which we live," but with them all other living men within the century in which it was framed, among whom to search, and they shall not be able to find the evidence of a single man agreeing with them.

Now, and here, let me guard a little against being misunderstood. I do not mean to say we are bound to follow implicitly in whatever our fathers did. To do so would be to discard all the lights of current experience—to reject all progress, all improvement. What I do say is, that if we would supplant the opinions and policy of our fathers in any case, we should do so upon evidence so conclusive, and argument so clear, that even their great authority, fairly considered and weighed, cannot stand; and most surely not in a case, whereof we ourselves declare they understood the question better than we.

If any part of the audience came with the expectation of hearing the rhetorical fire-works of a Western stump-speaker of the "half-horse, half-alligator" variety, they met novelty of an unlooked for kind. In Lincoln's entire address he neither introduced an anecdote nor essayed a witticism; and the first half of it does not contain even an illustrative figure or a poetical fancy. It was the quiet, searching exposition of the historian, and the terse, compact reasoning of the statesman, about an abstract principle of legislation, in language well-nigh as restrained and colorless as he would have employed in arguing a case before a court. Yet such was the apt choice of words, the easy precision of sentences, the simple strength of propositions, the fairness of every point he assumed, and the force of every conclusion he drew, that his listeners followed him with the interest and delight a child feels in its easy mastery of a plain sum in arithmetic.

With the sympathy and confidence of his audience thus enlisted, Lincoln next took up the more prominent topics in popular thought, and by words of kindly admonition and protest addressed to the people of the South, showed how impatiently, unreasonably, and unjustly they were charging the Republican party with sectionalism, with radicalism, with revolutionary purpose, with the John Brown raid, and kindred political offenses, not only in the absence of any acts to justify such charges, but even in the face of its emphatic and constant denials and disavowals. The illustration with which he concluded this branch of his theme could not well be surpassed in argumentative force.

But you will not abide the election of a Republican President! In that supposed event, you say, you will destroy the Union; and then you say, the great crime of having destroyed it will be upon us! That is cool. A highwayman holds a pistol to my ear, and mutters through his teeth, "Stand and deliver, or I shall kill you, and then you will be a murderer!" To be sure what the robber demanded of me—my money—was my own; and I had a clear right to keep it; but it was no more my own than my vote is my own; and the threat of death to me to extort my money, and the threat of destruction to the Union to extort my vote, can scarcely be distinguished in principle.

But the most impressive, as well as the most valuable, feature of Lincoln's address was its concluding portion, where, in advice directed especially to Republicans, he pointed out in dispassionate but earnest language that the real, underlying conflict was in the difference of moral conviction between the sections as to the inherent right or wrong of slavery, and in view of which he defined the proper duty of the free-States.