Prometheus shouts out his prophecy that Zeus, though he is confident now, will one day be destroyed by a far more powerful offspring who will be a better fighter and have recourse to greater weapons. This will fulfill the curse of Chronus, Zeus's own deposed father. Only Prometheus himself can prevent Zeus's downfall. The Chorus suggests that this is, perhaps, only Prometheus's wish, yet Prometheus replies that it will nevertheless happen. When the Chorus replies that Zeus might send further tortures and Prometheus should not say such things, Prometheus replies that the Oceanids may worship whomever they choose, but he himself foresees his tortures and is prepared for them.
Hermes, Zeus's messenger, enters and demands that Prometheus disclose the secret of Zeus's dangerous marriage. Prometheus responds that he is not afraid of these new gods, and that he will reveal nothing. Hermes exclaims that this sort of stubbornness is what got Prometheus in trouble in the first place, and Prometheus answers that he would rather be chained to the rock than be a slave to Zeus. Hermes accuses him of lacking wisdom. Prometheus mocks Hermes for thinking that he can be convinced to save Zeus through threats. Only his release will entice him to speak. Hermes threatens that Prometheus will be entombed within the rock and taken down to Tartarus, from which he will emerge much later only to have an eagle daily feast on his liver. This punishment will not end until another god agrees to go to Tartarus and take Prometheus's place.
The Chorus suggests that Hermes words are somewhat sensible, and Prometheus should put aside his stubbornness, but he replies that there is nothing shameful in suffering at the hand of an enemy and call on the earth to shake and take him into Tartarus amid bolts of lightning. Hermes responds that Prometheus is mad and tells the sympathetic Chorus to leave before they find themselves in the way of the coming thunder. The Oceanids turn on him, saying that they will stay with Prometheus because to betray a friend is the lowest act of all. Hermes responds that they should then not blame Zeus for their troubles, but realizes that they have brought them on themselves. Prometheus describes the storm around him and calls on Earth and Heaven to witness his suffering.
In this final and climactic section, the conflict between Zeus and Prometheus is stripped down to its most basic elements. Prometheus's love of humanity is not mentioned at all, and his theft of fire is only referred to once. Instead, the conflict is now presented as arising from Prometheus's refusal to obey Zeus's arbitrary laws. Zeus is once again shown to rule only through threats, while Prometheus's power lies in his refusal to cave in to those threats. He, too, has a powerful weapon against Zeus—his knowledge of the future marriage that will ruin the god—but he will not reveal it unless Zeus ends his threats and extends his friendship. Prometheus responds only to friendship and he will not answer to threats. Zeus rules only by threats and violates friendships. Both are extreme and obstinate in these positions. This is the essential nature of the conflict emphasized here.
The content of Prometheus's prophecies has reached the same extreme stage as his conflict with Zeus. While he has retained his temper so far, he now shouts out that Zeus will be destroyed, prompting Hermes's visit and the subsequent punishment. Prometheus has come to a stage in his development where he chooses to exacerbate the conflict rather than simply waiting for it to blow over. In the course of the play, Prometheus has gone through three stages in telling his prophecies. First, he spoke of his secret knowledge of Zeus's marriage as a means to his eventual deliverance and reconciliation with Zeus. In Io's presence, he spoke of his deliverance and Zeus's downfall without mention of any reconciliation. Here, in the final section, Prometheus speaks only of Zeus's downfall and practically ignores everything else. It seems odd that Prometheus's prophecy is now clearly false, since we know that Zeus was not defeated by his offspring. The explanation of why Prometheus would offer false prophecy seems to be that, in a sense, he is "only human." In other words, he sees two possible outcomes in the future, and he chooses one of those to insist on based on the extremity of his anger, which is now at its peak.
To emphasize the preceding point, we can note that reconciliation is mentioned only twice in this entire section, but the context in both cases is not one of prophecy. The first of these mentions is in a sarcastic context directed at Hermes. Prometheus states simply that he would be happy to repay kindness with kindness. Since Hermes does not seem to consider reconciliation a real possibility, the statement is clearly a sarcastic one designed to poke fun at Hermes attempts to elicit information. The second mention occurs when Prometheus insists that only his freedom will get him to talk, while threats are useless. Again, the intention here is not to suggest release and reconciliation as a possible future event, but only to contrast Zeus's way of doing business with Prometheus's own, since obedience is placed in opposition to friendship. Angered by Io's suffering and Hermes's arrogance, Prometheus seems to have abandoned reconciliation with Zeus as a possibility and awaits only Zeus's destruction. We see this state of mind echoed in Prometheus's utterances, as he has here switched from the conditional tense entirely to the future tense in speaking of Zeus's downfall. When Prometheus states that "time in its aging course teaches all things," he is saying not that Zeus will one day learn friendship, but only that he will one day understand suffering from personal experience.