On examination, then, the particulars of the classical tradition have shown extraordinary powers of survival, but not one of them has gone without protest and violation. The thousands of tragedies written during four centuries have all had marked resemblances, and all important developments have preserved relationships to the classical species; yet it is impossible to insist on any one quality of that species as essential, without encountering examples of great tragedies that lack it. The close relationships among these many plays forbid the separation of a few, distinguished by certain qualities, to be named as tragedies, and the rest as something else; and the great variations forbid the confident selection of any qualities as essential in the future development of tragedy. The modern amendments, though represented by nearly universal practice, have not saved the classical tradition, and are themselves coming under question. The plays of Ibsen, which seem to have instituted the most important development in tragedy for two centuries, return to something of the simplicity of action required by Aristotle, and present the struggle of individual wills as did Shakespeare, but are in prose and deal with contemporary bourgeois life,--a combination of relationships to the tradition wholly new. While idealization in some degree must be exercised in tragedy as in all forms of literature, it is impossible, in the light of realistic plays, to maintain that tragic effects can be secured only through the stories of exceptional persons. Tragic greatness, in the sense demanded by the theorists, is, indeed, scarcely more manifest in the persons of "Romeo and Juliet" than in those of "Hedda Gabler." While conflict of some kind is essential to a dramatic action, yet it may evidently be minimized without destroying the artistic impressiveness of suffering and disaster. Even the requirement that tragedy deal with the characters of individual men is being questioned. It is conceivable that plays in the future may, like Hauptmann's "The Weavers," turn from the emotions of the individual to those of a class, or may find their destructive and painful actions in the oppression, disaster, or mere unrest of the mass. Any precise and compact definition is sure to lack in comprehensiveness and veracity. It cannot sum up the facts of the past and present, much less set rules for the future. We seem forced to reject the possibility of any exact limitations for the dramatic species, to include as tragedies all plays presenting painful or destructive actions, to accept the leading elements of a literary tradition derived from the Greeks as indicating the common bonds between such plays in the past, but to admit that this tradition, while still powerful, is variable, uncertain, and unauthoritative.