the country was based on the then reasonable expectation that slavery would disappear, and that the nation would be all free.  It was reserved for modern political alchemists to discover the idea on which the leading politicians have been acting for thirty or forty years, that one half of a nation might believe in the fundamental principle on which the government is based, and the other half deny it, and yet the government go on harmoniously, wielding its powers acceptably and safely to all.  This is the error.  Our failure is not in the plan of government; the error is not that our fathers supposed that a government could be based and permanently sustained upon slavery and freedom advancing pari passu.  They indulged in no such delusion.  The error is modern.  When slavery demanded concessions, and freedom yielded; when slavery suggested compromises, and freedom accepted them; when slavery, unrebuked, claimed equal rights under the constitution, and freedom acknowledged the justice of the claim,—­then came the test whether the government itself should be administered in the service of slavery or in behalf of freedom.  Two considerations influenced the slaveholders.  First, even should they be permitted to wield the government, they foresaw that its provisions were inadequate to meet the exigencies of slavery.  No despotism can be sustained by the voluntary efforts of its subjects.  Slavery is a despotism; and as such can only be supported by power independent of that of the slaves themselves, and always sufficient for their control.  The slaves were yearly increasing in numbers and gaining in knowledge.  These changes indicated the near approach of the time when the slaves of the South would reenact the scenes of St. Domingo.  The plantations of the cotton region are remote from each other, and the proportion of slaves on a single plantation is often as many as fifty for every free person, The sale of negroes from the northern slave States has introduced an element upon the plantations at once intelligent and hostile, and, of course, dangerous, The time must come when the white populations of plantations, districts, or States even, would disappear in a single night, In such a moment of terror and massacre how, and to what extent, would the United States government, acting under the constitution, afford protection, aid, or even secure a barren vengeance?  These were grave questions, and admitted only of an unsatisfactory answer at best.  The government has power to put down insurrections; but for what good would a body of troops be marched to a scene of desolation and blood a fortnight or a month after the servile outbreak had done its work?  These considerations controlled the intelligent minds of the South, and they were driven irresistibly to the conclusion that the government of the United States was insufficient for the institution of slavery, even though the friends of slavery were entrusted with the administration.  What hope beyond?