In which ancient Greek poem does Hesiod first describe Pandora’s jar in detail?

Hesiod first describes Pandora’s jar in detail in Works and Days.

Works and Days is a didactic Greek poem traditionally attributed to Hesiod. It discusses farming, justice, labor, seafaring, and the hardships of human existence. Its Pandora episode explains why evils are found among people and why life requires continual work.

Hesiod also mentions Pandora in Theogony, but Works and Days provides the fuller narrative of her creation, marriage to Epimetheus, and the opening of the jar. The poem uses the myth as part of a larger account of the decline of human conditions and the consequences of Zeus’s will.

The object is a jar rather than a box in the Greek text. The familiar phrase arose much later through translation history. Because both Hesiodic poems are ancient, readers sometimes identify Theogony as the source of every Pandora detail, even though the jar episode belongs principally to Works and Days.