The Roman politician and philosopher Cicero tells the famous story about the tyrant Dionysius II of Syracuse and his courtier Damocles, which he had read in the History of Timaeus of Tauromenium. The anecdote is often told as a reminder that for a powerful man, there's always danger, although the real point of the story is that happiness is fragile.
This translation of Cicero's Tusculan disputations 5.61 was made by Gavin Betts.
Cicero on Damocles
[5.61] Indeed this tyrant himself gave his judgment as to how fortunate he was. For when one of his flatterers, Damocles, mentioned in conversation the wealth of Dionysius, the majesty of his rule, the abundance of his possessions, the magnificence of the royal palace and denied that there had ever been anyone more fortunate, he said, "So, Damocles, since this life delights you, do you wish to taste it yourself and make trial of my fortune?"
When Damocles said that he desired this, Dionysius gave orders that the man be placed on a golden couch covered with a most beautiful woven rug, embroidered with splendid works; he adorned many sideboards with chased silver and gold; then he gave orders that chosen boys of outstanding beauty should stand by his table and that they, watching for a sign from Damocles, should attentively wait on him; there were unguents and garlands; perfumes were burning; tables were piled up with the most select foods. Damocles seemed to himself fortunate.
In the middle of this luxury Dionysius ordered that a shining sword, fastened from the ceiling by a horse-hair, be let down so that it hung over the neck of that fortunate man. And so he looked neither at those handsome waiters nor the wonderful silver work, nor did he stretch his hand to the table. Now the very wreaths slipped off. Finally he begged the tyrant that he should be allowed to depart because he no longer wanted to be fortunate.