The modern English idiom meaning an action that creates many unexpected problems is “open Pandora’s box.”
The expression comes from the myth in which Pandora opens a container and releases troubles into the human world. In ordinary English, saying that someone has “opened Pandora’s box” means that an apparently simple action has unleashed complicated, harmful, or difficult consequences. The phrase can describe politics, technology, family disputes, or any situation in which problems multiply after a decision.
The idiom is related to, but not identical with, the ancient story. Hesiod described a jar, not a box, and did not formulate the modern phrase. “Pandora’s box” became established through later translation, literature, and visual culture. It is now one of the best-known mythological expressions in English, alongside phrases such as “Achilles’ heel” and “Herculean task.”