One of Aesop's Fables, a collection of stories that are believed to have been told by Aesop, a slave and storyteller who lived in ancient Greece between 620 and 564 BCE. In this story, a shepherd boy is watching over a flock of sheep. Bored and seeking excitement, he decides to falsely cry out that a wolf is attacking the sheep. The villagers come running to help, only to find out that the boy was lying. The boy finds their reaction amusing, so he plays the trick again with the same result. However, when a real wolf eventually does appear and the boy cries out for help again, the villagers don't believe him. The wolf attacks the flock, and the boy learns a painful lesson about the consequences of lying.
The moral of this story is usually stated as some version of "Liars are not believed even when they speak the truth," or more colloquially, "cry wolf too many times and people will stop believing you." The fable teaches the importance of honesty and the consequences of lying, particularly the erosion of trust. This story has been retold and adapted in countless forms over the years and is frequently used in educational settings to teach children about the importance of honesty. The phrase "crying wolf" has entered the English language as an idiom to refer to false alarms or deceitful behavior that leads people to ignore genuine warnings or issues.