Aristotle distinguishes between six different kinds of anagnorisis. First, there is recognition by means of signs or marks, such as when Odysseus's nurse recognizes him by virtue of a characteristic scar. Aristotle considers this the least artistic kind of anagnorisis, usually reflecting a lack of imagination on the part of the poet. Second, also distasteful to Aristotle, is a recognition contrived by the author. In such a case, the poet is unable to fit the anagnorisis into the logical sequence of the plot, and so it seems extraneous. Third is recognition prompted by memory. A disguised character may be prompted to weep or otherwise betray himself when presented with some memory from the past. Fourth, the second best kind of anagnorisis, is recognition through deductive reasoning, where the anagnorisis is the only reasonable conclusion of an agent's thought. Fifth, there is recognition through faulty reasoning on the part of a disguised character. The disguised character might unmask himself by exhibiting knowledge that only he could know. Sixth, the best kind of anagnorisis, is the kind of recognition that is naturally a part of the logical sequence of events in the play, such as we find in Oedipus Rex .
Aristotle makes seven final remarks about how a poet should go about constructing a plot: (1) The poet should be sure to visualize the action of his drama as vividly as possible. This will help him spot and avoid inconsistencies. (2) The poet should even try acting out the events as he writes them. If he can himself experience the emotions he is writing about, he will be able to express them more vividly. (3) The poet should first outline the overall plot of the play and only afterward flesh it out with episodes. These episodes are generally quite brief in tragedy but can be very long in epic poetry. As an example, Aristotle reduces the entire plot of the Odyssey to three sentences, suggesting that everything else in the poem is episode. (4) Every play consists of desis, or complication, and lusis, or denouement. Desis is everything leading up to the moment of peripeteia, and lusis is everything from the peripeteia onward. (5) There are four distinct kinds of tragedy, and the poet should aim at bringing out all the important parts of the kind he chooses. First, there is the complex tragedy, made up of peripeteia and anagnorisis; second, the tragedy of suffering; third, the tragedy of character; and fourth, the tragedy of spectacle. (6) The poet should write about focused incidents, and not about a whole epic story. For instance, a tragedy could not possibly tell the entire story of the Iliad in any kind of satisfying detail, but it can pick out and elaborate upon individual episodes within the Iliad. (7) The chorus should be treated like an actor, and the choral songs should be an integral part of the story. Too often, Aristotle laments, the choral songs have little to do with the action at all.
The discussion of anagnorisis is an elaboration on what we already found in Chapters 10 and 11. There, Aristotle suggested that anagnorisis is most effective when it is connected with peripeteia, as the two combined bring out a powerful tragic reversal that can arouse the emotions of pity and fear. Aristotle's sixth category of anagnorisis seems to suggest as much. The more tightly the moment of recognition is tied to the plot, the more effective it will be. For this reason, he opposes moments of recognition that are forced or contrived.
The seven points Aristotle makes at the end are, for the most part, either uninteresting or reiteration of what he has said before. For instance, a tragic poet likely knows far more about the actual process of writing a play than Aristotle does and hardly needs a philosopher's advice on visualizing and acting out the drama before writing it, which is what we find in (1) and (2). Points (3), (6), and (7) are further elaborations on the unity of plot, ensuring that the action and the chorus remain focused on the unified plot. Aristotle's discussion in (5) of the different kinds of tragedy is peculiar. It seems to contradict some of what he has said before, and he does little more than list these different types, leaving us to wonder exactly what he means by "tragedy of suffering" or "tragedy of character."
Of the seven points, by far the most interesting is (4), which concerns desis and lusis. The Greek word desis literally means "tying" and lusis means "untying," as does "denouement," the word we borrow from French. These two words give us a vivid metaphor for Aristotle's understanding of how a tragedy works: the plot is like a piece of string that is twisted up into a complex knot and then untied. The plot is thus structured around the moment of peripeteia, or reversal, where the knot begins to unravel. Every event before the peripeteia should serve to complicate the plot, and every event from the peripeteia onward should serve to untie these complications.
We also speak of knots to refer metaphorically to tension. A tragic plot builds up tension only to release it subsequently. This release of tension we find in the lusis might explain why Aristotle treats katharsis as a desired effect of tragedy.