Character is discussed in chapter xv as a distinct topic, but still with reference to plot. For throughout this section, especially from chapter xiii on, the topic is consistency.[41] Consistency, though it refers primarily to plot, must also include characterization. In general, characterization must be consistent with the morality of the individual purpose, with the moral habit of the social group, with the received idea of the person, and finally with itself.[42] In particular, it is necessary in the characters, as in the plan of the actions, to seek always the inevitable or the probable, so that the saying or doing of such-and-such things by such-and-such a person, just as the happening of this event after that, shall be inevitable or probable. Evidently, therefore, the solutions also [as well as the complications] of plots must come about from the plot itself, and not, as in the Medea ... by the _deus ex machina_.[43] In a word, consistency of characterization is part of the causal weaving of the plot. Chapter xvi applies the principle of consistency to “recognitions,” or “discoveries.”[44] Best discovery of all, however, is that which arises from the actions themselves, when the surprise comes as a natural result, as in the _Œdipus_ of Sophocles and in the _Iphigenia_.[45] Chapters xvii and xviii turn to the actual processes of dramaturgy, to the work of the playwright. This is concerned mainly with plot; but first Aristotle urges the fundamental necessity of visualizing. One must compose plots and work them out in the “lines” by putting [the scenes] before his eyes ... and as far as possible by acting out, even with the gestures.[46]... His stories, whether already made or of his own making, he must first set out in general (i.e., make a scenario), then put in the incidents and carry out.[47]... Every tragedy has both complication and solution, the events that precede [the opening scene] and often some of those within the play constituting the complication, and the rest the solution. By complication I mean all from the beginning to that scene which is just before the change in the hero’s fortunes; by solution, all from the beginning of the change to the end [of the play].[48]... It is necessary to remember what I have said often and not make a tragedy an epic system—by epic I mean aggregative—as if one should dramatize the whole story of the Iliad.[49]... The chorus too should be regarded as one of the actors, be a part of the whole and share in the action, be not as in Euripides, but as in Sophocles.[50] Visualizing actively at every stage, the playwright is to compose his plot before he works out his lines. He is to determine his play by the method of solution, to avoid the extensiveness of epic, and to make even the chorus contributory to the plot.