The importance of schylus in the development of the drama is immense. Before him tragedy had consisted of the chorus and one actor; and by introducing a second actor, expanding the dramatic dialogue thus made possible, and reducing the lyrical parts, he practically created Greek tragedy as we understand it. Like other writers of his time, he acted in his own plays, and trained the chorus in their dances and songs; and he did much to give impressiveness to the performances by his development of the accessories of scene and costume on the stage. "The Oresteia" is one of the supreme productions of all literature. It deals with the two great themes of the retribution of crime and the inheritance of evil; and here again a parallel may be found between the assertions of the justice of God by schylus and by the Hebrew prophet Ezekiel. Both contend against the popular idea that the fathers have eaten sour grapes and the children's teeth are set on edge; both maintain that the soul that sinneth, it shall die. The nobility of thought and the majesty of style with which these ideas are set forth give this triple drama its place at the head of the literary masterpieces of the antique world.