In Greek mythology, Pandora’s container was originally described as a jar.
The familiar phrase “Pandora’s box” comes from a translation tradition, not from the earliest surviving Greek wording. Hesiod’s Works and Days describes Pandora receiving a large storage jar, called a pithos, which contained evils that could escape into the world.
The Latin humanist Erasmus helped popularize the “box” version in the sixteenth century. The change may have arisen from translating or interpreting the Greek term as a container more like a small box. The jar detail matters because a pithos was a substantial vessel used for storing commodities such as grain or wine, rather than a modern decorative box.
The story is therefore often misremembered in a small but important way: the classic Greek myth has a jar, while “Pandora’s box” is the later English expression.