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: Abolitionism. The issue of slavery was further heightened by the rise of the Abolitionist movement in the 1820s and 1830s. Beginning in the North, adherents believed that slavery was morally wrong rather than simply a social evil.
The only cause of the war was that the South was invaded and responded to Northern aggression. I respectfully disagree with those who claim that the War Between the States was fought over slavery or that the abolition of slavery in the Revolutionary Era or early Federal period would have prevented war.