In Hesiod’s Works and Days, Pandora opened a jar, not a box.
The Greek word used by Hesiod is pithos, a large storage jar commonly used for grain, oil, or wine. In the myth, the jar contains destructive forces that escape into the human world when Pandora removes its lid. The story does not originally describe a small wooden box.
The familiar phrase “Pandora’s box” developed from a translation tradition. The Renaissance humanist Erasmus translated pithos into Latin as pyxis, meaning a box or small container, helping establish the wording that became standard in European languages. The mistranslation became so influential that the modern phrase now usually refers to the story itself.
Pandora’s jar should not be confused with ordinary domestic pottery: a pithos could be a very large vessel, sometimes taller than a person. Hesiod’s account is also distinct from later artistic versions, which often show Pandora holding a compact box because that image matches the popular expression.