In Greek mythology, Pandora opened a jar according to the earliest surviving account. Hesiod’s Works and Days describes a large storage vessel, called a pithos in Greek, rather than a small box.
The familiar phrase “Pandora’s box” developed later through translation history. In the sixteenth century, the humanist Erasmus translated the Greek vessel into the Latin word pyxis, meaning box or casket. That choice helped establish the expression used in modern English and many other languages.
The jar itself is important because it was a normal type of large earthenware container in the ancient Greek world. Modern retellings often picture a decorative box, but the older literary description is a storage jar. The story also differs between versions about whether Pandora deliberately opened it or whether the vessel was opened through curiosity or accident.