The rhythmical effects of diction and of choral dance are hardly more characteristic of Greek tragedy than its unvarying use of legendary themes and persons. Euripides is thought to have chafed within these confines, to have been hampered by the conventional prescription of old bottles for his new wine. In any age the playwright who insists on ideas in advance of his crowd thereby sacrifices something of the communal appeal. But even Euripides kept outwardly the unwritten law, and Aristotle[8] accepted it as part of his theory. It is evident that such themes and such persons were a tragic convention; but the convention was still recognized in the middle ages;[9] it was accepted by the Renaissance; it was formally adopted by the French seventeenth century; and its being a convention does not prove it any the less dramatic. Without disparaging the gain to modern tragedy from the widening of the tragic field we may take account of the typical values of the field of tradition. The field of tradition is _ipso facto_ the field of communal memories and aspirations and, even in modern times, of myth. Though the re-creation of myth may be artificial and remote, that it need not be so, that it may on the contrary originally express both the poet and the conceptions of his audience, has been proved many times, and very convincingly in our own time by William Vaughn Moody’s _Fire-bringer_. The fire of Prometheus is there seen, even after Æschylus, even after Shelley, to be undying. The modern science of anthropology, indeed, gives good ground for thinking both that myth is constantly human and that by its very persistence, as of a primitive trait, it opens opportunities for drama.