As a key to understanding the meaning of slavery in America, the Missouri controversy of 1819-21 is probably our most valuable text. The heat of sectional rhetoric during the Missouri debates reached a level never exceeded, and rarely matched, until the secession crisis of 1860. Moreover, nearly all the arguments for and against slavery in America were advanced at this time (with revealing exceptions, as we shall see). The Missouri Compromise is said to have settled the slavery question for a generation; its repeal, in 1854, triggered the final stage of the sectional crisis, prompted the establishment of the Republican Party, and impelled the return to politics of Abraham Lincoln. It merits a heading in every American history textbook. ----Introduction.