Aristotle now narrows his focus to examine tragedy exclusively. In order to do so, he provides a definition of tragedy that we can break up into seven parts: (1) it involves mimesis; (2) it is serious; (3) the action is complete and with magnitude; (4) it is made up of language with the "pleasurable accessories" of rhythm and harmony; (5) these "pleasurable accessories" are not used uniformly throughout, but are introduced in separate parts of the work, so that, for instance, some bits are spoken in verse and other bits are sung; (6) it is performed rather than narrated; and (7) it arouses the emotions of pity and fear and accomplishes a katharsis (purification or purgation) of these emotions.
Next, Aristotle asserts that any tragedy can be divided into six component parts, and that every tragedy is made up of these six parts with nothing else besides. There is (a) the spectacle, which is the overall visual appearance of the stage and the actors. The means of imitation (language, rhythm, and harmony) can be divided into (b) melody, and (c) diction, which has to do with the composition of the verses. The agents of the action can be understood in terms of (d) character and (e) thought. Thought seems to denote the intellectual qualities of an agent while character seems to denote the moral qualities of an agent. Finally, there is (f) the plot, or mythos, which is the combination of incidents and actions in the story.
Aristotle argues that, among these six, the plot is the most important. The characters serve to advance the action of the story, not vice versa. The ends we pursue in life, our happiness and our misery, all take the form of action. That is, according to Aristotle, happiness consists in a certain kind of activity rather than in a certain quality of character. Diction and thought are also less significant than plot: a series of well-written speeches have nothing like the force of a well-structured tragedy. Further, Aristotle suggests, the most powerful elements in a tragedy, the peripeteia and the anagnorisis, are elements of the plot. Lastly, Aristotle notes that forming a solid plot is far more difficult than creating good characters or diction.
Having asserted that the plot is the most important of the six parts of tragedy, he ranks the remainder as follows, from most important to least: character, thought, diction, melody, and spectacle. Character reveals the individual motivations of the characters in the play, what they want or don't want, and how they react to certain situations, and this is more important to Aristotle than thought, which deals on a more universal level with reasoning and general truths. Melody and spectacle are simply pleasurable accessories, but melody is more important to the tragedy than spectacle: a pretty spectacle can be arranged without a play, and usually matters of set and costume aren't the occupation of the poet anyway.
Aristotle's definition of tragedy at the beginning of this chapter is supposed to summarize what he has already said, but it is the first mention of the katharsis. The Greek word katharsis was usually used either by doctors to talk about purgation, the flushing of contaminants out of the system, or by priests to talk about religious purification. In either case, it seems to refer to a therapeutic process whereby the body or mind expels contaminants and becomes clean and healthy. Determining exactly what role katharsis is meant to play in tragedy is somewhat more difficult.
First, we might ask what exactly katharsis is in reference to tragedy. The idea, it seems, is that watching a tragedy arouses the emotions of pity and fear in us and then purges these emotions. But, by virtue of mimesis, we aren't feeling real pity or real fear. I may feel pity for Oedipus when he learns that he has killed his father and married his mother, but this is a different kind of pity than the pity I feel for the homeless or for those living in war zones. I know that Oedipus is not a real person and that no one is really suffering when I watch Oedipus suffer. As a result, I can empathize with the character of Oedipus without feeling any kind of guilt or obligation to help him out. Watching tragedy has a cathartic effect because I can let go of the emotional tension built up in me as I leave the theater. I am able to experience profound emotion without having its consequences stay with me and harden me to subsequent emotional shocks.
Second, we might ask to what extent katharsis is the purpose of tragedy, and to what extent it is an occasional effect of tragedy. The question of in what way art may be good for us is a very difficult question to answer. The best art (and this applies to Greek tragedy) is not didactic: it does not try to tell us outright how we ought or ought not to behave. At the same time, there is definitely a lot we can learn from a subtle appreciation of art. The value of art, on the whole, seems to stem more from its ability to arouse emotion and awareness on an abstract, general level, rather than to teach us particular truths. Oedipus Rex is valuable because it engenders a certain state of mind, not because it teaches us to avoid marrying older women whose family histories are uncertain.
Though katharsis may be an important effect of tragedy, it is hardly the reason for which poets write tragedies. If that were so, poets would be little more than emotional therapists. Again, Aristotle is writing as an observer more than as a theorist. He has observed that tragedy has a cathartic effect on its viewers, but he is not trying to enunciate this as the end goal of all tragedy.
The other important concept we encounter in this chapter is that of mythos. While "plot" is a pretty good translation of this word in reference to tragedy, mythos can be applied to sculpture, music, or any other art form. The mythos of a piece of art is the way it is structured and organized in order to make a coherent statement. Thus, when Aristotle speaks about the "plot" of a tragedy, he is not just referring to who did what to whom, but is speaking about how the events in the story come together to bring out deeper, general themes.
Plot, then, is central to a tragedy, because that is where, if at all, its value lies. If character were central to tragedy, we would be watching Oedipus Rex in order to learn something about Oedipus, about what makes him tick, or how he reacts in different situations. The character of Oedipus in itself is uninteresting: why should we care about the personality of someone who never existed? The value of Oedipus lies in what we can learn about ourselves and our world from observing his fate. What we learn from a tragedy—the effect it has on us—results from the way it is structured to draw our minds toward general truths and ideas; that is, from its mythos.