Pandora’s box is an artifact in Greek mythology, taken from the myth of Pandora’s creation in Hesiod’s Works and Days. The “box” was actually a large jar given to Pandora, which contained all the evils of the world. Pandora opened the jar and all the evils flew out, leaving only “Hope” inside once she had closed it again.
Today the phrase “to open Pandora’s box” means to perform an action that may seem small or innocent, but that turns out to have severely detrimental and far-reaching negative consequences. The action cannot be reversed.
The original Greek word was ‘pithos’, which is a large jar, sometimes as large as a small person (Diogenes of Sinope was said to have slept in one). It was used for storage of wine, oil, grain or other provisions, or, ritually, as a container for a human body for burying. In the case of Pandora, this jar may have been made of clay for use as storage as in the usual sense, or of metal, such as bronze, as an unbreakable prison. Remember Marion in the jar in Indiana Jones, Raiders of the Lost Ark?
The mis-translation of pithos is usually attributed to the 16th century humanist Erasmus of Rotterdam who translated Hesiod’s tale of Pandora into Latin. Erasmus rendered pithos as the Greek pyxis, meaning “box”. The phrase “Pandora’s box” has endured ever since. This misconception was further reinforced by Dante Gabriel Rossetti’s painting Pandora.
I took the “Jar” concept a little further. You can read about it in the tension-filled climax of Seven Lamps!