Hesiod tells the full jar-opening episode in his poem Works and Days.
Hesiod was an early Greek poet generally dated to the late eighth or early seventh century BCE. Works and Days combines practical advice about farming and justice with myths explaining humanity’s difficult condition, including the story of Pandora and her container.
The Pandora episode follows the conflict between Zeus and Prometheus. After Prometheus steals fire for humans, Zeus orders the gods to create a woman who receives gifts from them. She is sent to Epimetheus, who accepts her despite Prometheus’s warning. When Pandora opens the jar, evils spread among humans and Hope remains inside.
Hesiod’s Theogony also discusses the creation of women in connection with the Prometheus story, but it does not narrate the jar-opening episode in the same detailed way. This distinction matters because modern summaries sometimes merge details from both poems.