Greek mythology, any discussion of two opposing dangers called for Scylla and Charybdis. Scylla was a rock shoal off the coast of Italy. Charybdis was a whirlpool on the coast of Sicily, not far away. Sailors knew they would be doomed if they strayed too far in either direction. Forecasters should feel the same about under- and overreaction to new information, the Scylla and Charybdis of forecasting. Good updating is all about finding the middle passage.
