WikiPedia:Damocles1
Damocles was an excessively flattering courtier in the court of Dionysius II of Syracuse, a 4th Century BC tyrant of Syracuse, Italy. He exclaimed that, as a great man of power and authority, Dionysius was truly fortunate. Dionysius offered to switch places with him for a day, so he could taste first hand that fortune. In the evening a banquet was held, where Damocles very much enjoyed being waited upon like a king. Only at the end of the meal did he look up and notice a sharpened sword hanging by a single piece of horsehair directly above his head. Immediately, he lost all taste for the fine foods and beautiful boys and asked leave of the tyrant, saying he no longer wanted to be so fortunate.
The Sword of Damocles is a frequently used allusion to this tale, epitomizing the imminent and ever-present peril faced by those in positions of power. More generally, it is used to denote a precarious situation and sense of foreboding thereof, especially one in which the onset of tragedy is restrained only by a delicate trigger or chance. Moreover, it can be seen as a lesson in the importance of understanding someone’s experience.