In case you forgot, this play is called Prometheus Bound—not Prometheus Skipping Merrily Along and Doing Jumping Jacks. For pretty much the whole stinkin' play, the big guy is chained to a rock in the barren wasteland of Scythia. And yet, he's not the only one all tied up. In his view, he has much more freedom than characters like the god Hermes, who blindly carry out the orders given to them by Zeus, without using any of that expensive, liberal arts critical thinking. So, which is worse: mental or physical confinement?
According to Prometheus, his form of physical confinement is not as bad as Hephaestus's, Oceanus's, and Hermes's mental slavery to Zeus.
Because even Zeus is confined by the Fates, nobody in the play is actually free.