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.
These two parts were the southern states known as Confederacy and Northern states known as Union. The main and the declared cause of the conflict was the issue of abolition of slavery. However there were many other underlying issues adding to the conflicts that resulted in the war.