I don't think I've ever seen anything Classical mentioned in Dear Abby, so when something is, we make note of it:

Dear Abby: I have often heard the saying "That would be like opening Pandora's box." Where did that phrase originate?
Yvonne in Norlina, N.C.

Dear Yvonne: It refers to a story from Greek mythology. The box was a gift to Pandora from the gods, but was given with the warning that she should never open it. When curiosity got the better of Pandora and she opened it anyway, a swarm of evils was loosed upon mankind.

... but what was left in the box, Abby?