In contrast to earlier works of scholarship directed towards resolving the problems of authenticity and date of composition through considerations of metre, language, and style, there has been a tendency for more recent studies of the Prometheus Bound to concentrate upon those aspects of thematic development which some have seen repeated in the Supplices, now dated to 464–463 B.c., and the Oresteia of 458. So, for instance, C. J. Herington has demonstrated on more than one occasion the apparent divergence that exists between the cosmic system portrayed by Aeschylus in the Persae and Septem and that found in the later plays, including the Prometheus. In the former group he says: ‘the Divine is united against man: let a human being swerve by a hair's-breadth from the rules, and the powers of earth and heaven will join together to castigate him’, while in the later plays ‘the human and divine cosmos is divided into the enemy camps of male and female, and of the opposites that go with them respectively: light/dark, heaven/earth, new/old; the universal fabric is torn in two.’ Certainly the ideas he puts forward here are acceptable in the case of the Oresteia, but for their extension to the Supplices and Prometheus they depend largely upon reconstructions of the lost plays that made up their respective trilogies: a hazardous course, though perhaps not altogether unjustified in the light of the available evidence.