As for the plots themselves, their main feature is that deliberate complexity which we have called intrigue and which was made possible by the poet’s use of a third actor. After the great achievements of Æschylus it became necessary to add some fresh kind of interest; this Euripides found in a readjustment of sympathies, Sophocles in an increase of dramatic thrill. It is an exciting moment in the _Trachiniæ_ when, just as Deianira is about to re-enter the palace, the messenger mysteriously draws her apart and reveals the truth about the captive Iole. The magnificent death-scene of Ajax is the outcome of the cunning wherewith he has thrown his friends off the scent. The _Electra_ is full of this method; the mission of Chrysothemis is turned into a weapon against the murderess who sent her, and the episode of Orestes’ funeral-urn is a magnificent piece of dramatic artistry. In the _Œdipus Tyrannus_ the king brings about his own fatal illumination by sending for the herdsman. The _Philoctetes_, above all, is filled with the deliberate plotting of Odysseus. The marked increase in complexity which Sophocles’ work thus shows as compared with that of Æschylus is undoubtedly the chief (perhaps the only) reason for his desertion of the trilogy form.[400] Side by side with this attention to mechanism is that curious indifference to the fringes of the plot which we have had occasion to notice in several places. Another characteristic of Sophocles is that famous “tragic irony” by which again he imparts new power to old themes. It turns to magnificent profit a circumstance which might seem to vitiate dramatic interest—the fact that the spectator knows the myth and therefore cannot be taken by surprise. Between an audience which foresees the event, and the stage-personages who cannot, the playwright sets up a thrilling interest of suspense. He causes his characters to discuss the future they expect in language which is fearfully and exquisitely suitable to the future which actually awaits them. Ajax, while his madness still afflicts him, stands amid the slaughtered cattle and proclaims his triumph over the Greek chieftains, just before he awakes to the truth that by his “triumph” he has ruined himself. More elaborate is the scene in which Deianira explains her stratagem of the robe which is to bring back the love of Heracles. But the _Œdipus Tyrannus_ provides by far the finest instance. As the king in scene after scene accumulates horror upon his own unconscious head, the spectator receives, always at the right moment and in full measure, the impact of increasing disaster. Yet since his perception is a discovery which he himself has made, horror is tempered by an intellectual glow, a spiritual exaltation.