When Shelley wrote "Prometheus Unbound", the authorship of the "Prometheia" and its connection as a trilogy was not in question. Of the three works, "Prometheus Bound" is the only tragedy that survived intact, although fragments of "Prometheus Unbound" remained, allowing a fairly detailed outline based on the Prometheus myth told by Hesiod and extensive prophesying in the first work. It is this assumed trilogy, including Prometheus' reconciliation with Zeus, thought to occur in the final part of the cycle, which Shelley considers in the introduction.