In the spring of 1860, Mr. Lincoln yielded to the urgent calls which came to him from the East for his aid in the exciting canvasses then in progress in that section, and spoke at various places in Connecticut, New Hampshire, and Rhode Island, and also in New York city, and was everywhere warmly welcomed by immense audiences. Without doubt, one of the greatest speeches of his life was that delivered by him in the Cooper Institute, in New York, on the 27th of February, 1860, in the presence of a crowded assembly which received him with the most enthusiastic demonstrations. We subjoin a full report of this masterly analysis of men and measures. After being introduced in highly complimentary terms by the venerable William Cullen Bryant, who presided on the occasion, he proceeded: “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 any thing 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: “‘Our fathers, when they framed the Government under which we live, understood this question just as well, and even better than we do now.’ “I fully indorse this and I adopt it as a text for this discourse. I so adopt it because it furnishes a precise and agreed starting point for the discussion between Republicans and that wing of Democracy headed by Senator Douglas. It simply leaves the inquiry: ‘What was the understanding those fathers had of the questions mentioned?’ “What is the frame of Government under which we live? “The answer must be: ‘The Constitution of the United States.’ That Constitution consists of the original, framed in 1787 (and under which the present Government first went into operation), and twelve subsequently framed amendments, the first ten of which were framed in 1789. “Who were our fathers that framed the Constitution? I suppose the ‘thirty-nine’ who signed the original instrument may be fairly called our fathers who framed that part of the present Government. It is almost exactly true to say they framed it, and it is altogether true to say they fairly represented the opinion and sentiment of the whole nation at that time. Their names being familiar to nearly all, and accessible to quite all, need not now be repeated. “I take these ‘thirty-nine,’ for the present, as being ‘our fathers who framed the Government under which we live.’ “What is the question which, according to the text, those fathers understood just as well, and even better than we do now?