The Missouri question marked a distinct era in the political thought of the country, and made a profound impression on the minds of patriotic men. Suddenly, without warning, the North and the South, the free States and the slave States, found themselves arrayed against each other in violent and absorbing conflict. During the interval between the adoption of the Federal Constitution and the admission of Missouri, there had been a great change in the Southern mind, both as to the moral and the economic aspects of slavery. This revolution of opinion had been wrought in large degree by the cotton-plant. When the National Government was organized in 1789, the annual export of cotton did not exceed three hundred bales. It was reckoned only among our experimental products. But, stimulated by the invention of the gin, production increased so rapidly, that, at the time of Missouri's application for admission to the Union, cotton-planting was the most remunerative industry in the country. The export alone exceeded three hundred thousand bales annually. But this highly profitable culture was in regions so warm that outdoor labor was unwelcome to the white race. The immediate consequence was a large advance in the value of slave-labor, and in the price of slaves. This fact had its quick and decisive influence, even in those slave-holding States which could not raise cotton. The inevitable and speedy result was a consolidation of the political power necessary to protect an interest at once so vast and so liable to assault. It was not unnatural that this condition should lead to a violent outburst on the slavery question, but it was nevertheless wholly unexpected. The causes which let to it had not been understood and analyzed. The older class of statesmen, who had come down from the period of the Revolution, from the great work of cementing the Union and framing the Constitution, deplored the agitation, and viewed the results with the gravest apprehension. The compromise by a geographical line, dividing the slave States from the free, was regarded by this class of patriots as full of danger,--a constant menace to the peace and perpetuity of the Union. To Mr. Jefferson, still living in vigorous old age, the trouble sounded like an alarm- bell rung at midnight. While the measure was pending in Congress, he wrote to a member of the House of Representatives, that "the Missouri question is the most portentous one which has ever threatened the Union. In the gloomiest hour of the Revolutionary war I never had any apprehensions equal to those which I feel from this source." Men on both sides of the controversy began to realize its significance and to dread its probable results. They likened the partition of the country by a geographical line unto the ancient agreement between Abraham and Lot, where one should go to the right, and the other to the left, with the certainty of becoming aliens, and the possibility of becoming enemies.