Concerning Plot, which he rightly calls “the soul of a tragedy,”[129] Aristotle is of course far more copious. The salient points alone can be set down here:—
(a) “The proper magnitude is comprised within such limits, that the sequence of events, according to the law of probability or necessity, will admit of a change from bad fortune to good, or from good fortune to bad.”[130]
(b) “The plot ... must imitate one action and that a whole, the structural union of the parts being such that if anyone of them is displaced or removed, the whole will be disjointed and disturbed.”[131] A tragedy must be an organism. It therefore follows that “of all plots and actions the episodic are the worst ... in which the episodes or acts succeed one another without probable or necessary sequence”.[132] He is recommending the “Unity of Action”.
(c) “Plots are either Simple or Complex.... An action ... I call Simple, when the change of fortune takes place without Reversal (or Recoil) of the Action and without Recognition. A Complex Action is one in which the change is accompanied by such Reversal, or by Recognition, or by both.”[133] Reversal we shall meet again. By Recognition Aristotle means not merely such Recognition-scenes as we find in the crisis of the Iphigenia in Tauris (though such are the best) but “a change from ignorance to knowledge, producing love or hate between the persons destined by the poet for good or bad fortune”.[134]
(d) “Two parts, then, of the plot—Reversal and Recognition—turn upon surprises. A third part is the Tragic Incident. The Tragic Incident is a distinctive or painful action, such as death on the stage, bodily agony, wounds, and the like.”[135] In the words “death on the stage”—or “before the audience” (the phrase[136] has no bearing on the stage-controversy), Aristotle casually but completely overthrows another critical convention, that in ancient Tragedy deaths take place only “behind the scenes”. In the extant plays, not only do Alcestis and Hippolytus “die on the stage” in their litters, but Ajax falls upon his sword.
(e) The best subject of Tragedy is the change from good fortune to bad in the life of some eminent man not conspicuously good and just, whose misfortune, however, is due not to wickedness but to some error or weakness.[137]
(f) The poet “may not indeed destroy the framework of the received legends—the fact, for instance, that Clytæmnestra was slain by Orestes and Eriphyle by Alcmæon—but he ought to show invention of his own, and skilfully handle the traditional material”.[138] This injunction was obeyed beforehand by all the three Athenian masters; it is especially important to remember it when studying Euripides.
(g) “The unravelling of the plot ... must arise out of the plot itself; it must not be brought about by the Deus ex Machina, as in the Medea.... The Deus ex Machina should be employed only for events external to the drama—for antecedent or subsequent events, which lie beyond the range of human knowledge.”[139] This vital criticism will be considered later, when we discuss the Philoctetes[140] of Sophocles and the Euripidean drama.[141]
(h) “Within the action there must be nothing irrational. If the irrational cannot be excluded, it should be outside the scope of the tragedy. Such is the irrational element in the Œdipus of Sophocles.”[142] Aristotle means certain strange data in the Œdipus Tyrannus—the fact that neither Œdipus nor Jocasta has learnt earlier about the past, and so forth.