Most literary and theater historians emphasize the historical importance of Ibsen, Strindberg, and Andre Antoine's Theatre Libre and as a consequence Shelley's Prometheus Unbound is reduced to a parenthesis in the history of drama. Can contemporary views on tragedy expressed in theoretical works by Hans-Thies Lehmann and put on stage by, for example, Jan Fabre, Romeo Castellucci, and Olivier Dubois, cast a new light on Shelley's play and make it more familiar with the stage? Prometheus Unbound does not replace the lost play of the trilogy of Aeschylus. Rather, it questions the premises of the Greek play and it is to a certain extent a metadrama. The concept of excess, central to Lehmann and Fabre, is one of the characteristics of Shelley's drama. The Aristotelian concept of opsis, neglected in eighteenth- and nineteenth-century tragedy theory, is fundamental in Prometheus Unbound just as are music and voices. Prometheus Unbound is a typically Romantic drama as its action takes place on several levels at the same time: on stage and on a cosmic level, on stage and in a phantom world, on stage and in the mind. The use of metaphors and similes (as, like) are consitutive of the play and they constantly draw our attention to new modalities (memories, dreams, visions) and back again and thus make the modality of the action insecure. In these respects, Shelley's drama can be looked upon as a forerunner of the avantgarde theater of today.