What modern expression, based on Pandora’s myth, means starting a chain of unexpected problems?

The modern expression “open Pandora’s box” means starting a chain of unexpected problems.

The idiom comes from the myth in which Pandora opens a sealed container and releases evils into the human world. In modern English, it is used figuratively when an action creates many complications that were difficult to foresee or control. The expression can apply to politics, technology, personal decisions, or any situation where one discovery leads to numerous consequences.

The phrase is based on the later “box” version of the story, although Hesiod’s ancient Greek container was a pithos, or jar. This translation history explains why the idiom uses “box” rather than “jar.” The expression does not usually refer to a single isolated problem; it suggests a broad and escalating set of troubles.

“Open Pandora’s box” is different from “let the genie out of the bottle,” another expression about irreversible consequences. The Pandora idiom specifically invokes the Greek myth and its release of evils, with hope traditionally associated with what remains inside.