Hesiod's Works and Days and Theogony, written circa 700 BC, are early and major sources for stories of Greek mythology, and sources for Aeschylus. Hesiod's Theogony contains the starting point for Aeschylus' play, which was written more than two centuries later. However by the time that Aeschylus read the Theogony, it had accrued significant additions that are now part of the extant version. Parts of those additions — including the story of Hercules killing the eagle — are essential to Aeschylus' conception of Prometheus Bound. Aeschylus also added his own variations. For example, in Hesiod Prometheus' efforts to outwit Zeus are simply presented, without noting that Zeus' response is overly cruel, or that Prometheus' actions might be justified — that Zeus became angry was enough for Hesiod to report without question. Aeschylus looks at those events in Hesiod, and sees intolerable injustice.[16]
Another departure by Aeschylus from Hesiod's Theogony involves the two forms of punishment of Prometheus — the chaining to a rock, and the eagle's daily tearing of his liver. In the version of the Theogony that Aeschylus was familiar with, which is also the extant version known to modern readers, the two punishments are presented as one story. It was Aeschylus, who instead decided to separate the tortures, and have the eagle begin tearing at Prometheus' liver only after the chained Prometheus had refused to reveal the secrets that Zeus wanted to know.[17] Aeschylus' alterations have been maintained by literature that followed Prometheus Bound.[16]
Hesiod portrays Prometheus as a lowly trickster and semi-comic foil to Zeus's authority. Zeus's anger toward Prometheus is in turn responsible for mortal man's having to provide for himself; before, all of man's needs had been provided by the gods. Prometheus' theft of fire also prompts the arrival of the first woman, Pandora, and her jar of evils. Pandora is entirely absent from Prometheus Bound, where Prometheus becomes a human benefactor and divine kingmaker, rather than an object of blame for human suffering.[18]
