Damocles was a member of the court of Dionysius, ruler of the Sicilian city of Syracuse during the 300s B . C . According to a legend passed on by the Roman writer Cicero, Damocles told Dionysius how much he envied his kingly wealth, power, and happiness. In response, Dionysius invited Damocles to come to a magnificent banquet.
imminent about to take place; threatening
Damocles was seated before a marvelous feast, when he happened to glance up in horror. Above his head hung a sharp sword, suspended by nothing more than a single thread. In this way, Dionysius showed Damocles that a ruler's life may appear grand, but it is filled with uncertainty and danger. The "sword of Damocles" has thus come to symbolize imminent danger.