In Hesiod’s account of Pandora’s box, the troubles were held in a jar. The Greek text uses the word pithos, a large storage vessel commonly used for grain, oil, or other goods.
Pandora opens the container after receiving it as part of the myth’s punishment of humanity. Once opened, the illnesses, hardships, and other evils inside escape and spread among mortals. Hope remains inside when Pandora closes the vessel.
The phrase “Pandora’s box” became standard because the Renaissance scholar Erasmus translated pithos into the Latin pyxis, meaning a box or small container. That choice strongly shaped the version known in modern European languages.
The jar detail matters because a pithos was much larger and more practical than the decorative box shown in many modern illustrations. The story’s central image is therefore a large household or storage vessel transformed into a mythic container of human suffering.