The influence of the Southern States in the national politics was due mainly to the fact of their having a single interest on which they were all united, and, though fond of contrasting their more chivalric character with the commercial spirit of the North, it will be found that profit has been the motive to all the encroachments of slavery. These encroachments first assumed the offensive with the annexation of Texas. In the admission of Missouri, though the Free States might justly claim a right to fix the political destiny of half the territory, bought with the common money of the nation, and though events have since proved that the compromise of 1820 was a fatal mistake, yet, as slavery was already established there, the South might, with some show of reason, claim to be on the defensive. In one sense, it is true, every enlargement of the boundaries of slavery has been an aggression. For it cannot with any fairness be assumed that the framers of the Constitution intended to foreordain a perpetual balance of power between the Free and the Slave States. If they had, it is morally certain that they would not so have arranged the basis of representation as to secure to the South an unfair preponderance, to be increased with every addition of territory. It is much more probable that they expected the Southern States to fall more and more into a minority of population and wealth, and were willing to strengthen this minority by yielding it somewhat more than its just share of power in Congress. Indeed, it was mainly on the ground of the undue advantage which the South would gain, politically, that the admission of Missouri was distasteful to the North.