I am obliged to confess that I do not regard the abolition of slavery as a means of warding off the struggle of the two races in the Southern states. The Negroes may long remain slaves without complaining; but if they are once raised to the level of freemen, they will soon revolt at being deprived of almost all their civil rights; and as they cannot become the equals of the whites, they will speedily show themselves as enemies.
Chapter XVIII. - Democracy in America, Volume I (1835) - Chapter XV-IXX