In Play I, Part III, the Chorus speaks at length of how they suddenly feel danger and foreboding, but don't know exactly why. The poetry of the speech develops an extended metaphor of life being like a sailing ship, which even when sailing calmly and smoothly can suddenly and unavoidably strike an unseen rock, adding that even if some of that ship's valuable cargo is lost, the ship itself will continue to function and maintain its glorious progress.
The Oresteia