"When we consider the cruelty of the origin of negro slavery, its nature, the character of the free institutions of the whites, and the irresistible progress of public opinion throughout America, as well as in Europe, it is impossible not to anticipate frequent insurrections among the blacks in the United States; they are rational beings like ourselves, capable of feeling, of reflection, and of judging of what naturally belongs to them as a portion of the human race. By the very condition of the relation which subsists between us, we are enemies of each other. They know well the wrongs which their ancestors suffered at the hands of our ancestors, and the wrongs which they believe they continue to endure, although they may be unable to avenge them. They are kept in subjection only by the superior intelligence and superior power of the predominant race." At the North, anti-slavery sentiments had intensified; at the South, where slavery was at first regarded as an evil, the consequent ease and wealth from slave labor had changed public opinion, and had made the people jealous of northern discussion. Through the invention of the cotton-gin, by Eli Whitney, the value of cotton exports had quadrupled in twenty years, and the value of slaves had trebled. Comparatively good feeling was maintained by the two sections of the country as long as for every slave State admitted to the Union a free State was also admitted. In 1818, the people of Missouri desired to be admitted to the Union. Mr. Tallmadge of New York proposed that the further introduction of slavery should be prohibited, and that all children born within the said State should be free at the age of twenty-five years. The discussion grew strong and bitter. Two years later the inhabitants of the State proceeded to adopt a constitution which forbade free negroes from coming into the territory or settling in it. The discussion grew more bitter still. Threats of disunion and civil war were heard. Jefferson wrote from his Monticello home, "The Missouri question is the most portentous one that ever threatened the Union. In the gloomiest moments of the Revolutionary War I never had any apprehension equal to that I feel from this source." A senator from Illinois, Mr. Thomas, proposed that no restriction as to slavery be imposed upon Missouri, but that in all the rest of the territory ceded by France to the United States, north of 36° 30', this being the southern boundary of Missouri, there should be no slavery. Then Mr. Clay, with his intense love for the Union, bent all his energies to effect this compromise suggested by Thomas. He spoke earnestly in its behalf, and went from member to member, persuading and beseeching with all his genius and winsomeness. When Clay had effected the passage of the bill, the "great pacificator" became more beloved than ever. He had saved the Union, and now was talked of as the successor to President Monroe.