In Greek mythology, Pandora’s original vessel is called a pithos in Hesiod’s Works and Days. A pithos was a large storage jar used in the ancient Greek world, commonly for products such as grain, oil, or wine.
The familiar phrase “Pandora’s box” is therefore a later translation and transmission change. Hesiod’s Greek text uses pithos, not a word meaning a small hinged box. Erasmus’s Latin rendering helped establish the “box” wording in European languages, and that version eventually became the standard expression in English.
A pithos could be large and substantial, sometimes standing nearly as tall as a person. Its practical storage function makes the image different from the compact decorative box shown in many modern illustrations. The myth’s central action remains the opening of a container and the release of destructive forces, but the object’s physical form changed in popular culture.
This is why “Pandora’s box” is culturally correct as an idiom while “Pandora’s jar” is closer to Hesiod’s original wording.