riddle - separate with a riddle, as grain from chaff screen sift, sieve, strain - separate by passing through a sieve or other straining device to separate out coarser elements; sift the flour
Causes of the Civil War: Bleeding Kansas. Proposed by Sen. Stephen Douglas of Illinois, the Kansas-Nebraska Act essentially repealed the line imposed by the Missouri Compromise. Douglas, an ardent believer in grassroots democracy, felt that all the territories should be subject to popular sovereignty.
The salient cause of the Civil War was the conflict between slave and free states over the future of slavery in the United States. The conflict was kept from boiling over in the early decades of the 19th century because of political compromises and a rough equivalence between the numbers of slave and free states.