No word or work of mine – nothing can be revoked,
there is no treachery, nothing left unfinished
once I bow my head to say it shall be done.

– Homer

The Iliad, Book 1, lines 629-631. Zeus explains the absolute power of his will to Thetis, mother of Achilles. Thetis wants Zeus to honor her son by granting victory to the Trojans while Achilles remains out of the battle. Zeus reluctantly agrees, indicating that the fate of humans is very much in the hands of the gods.