Aristotle's Poetics was written in approximately 335 BC, in part to summarize the characteristics of the tragic plays from ancient Greece. One such characteristic that Aristotle noted was that tragedies should evoke from the audience the emotions of pity and fear. The evocation of these feelings is what Aristotle defined as catharsis, or, in the adjective form, the cathartic process.

Aristotle's ideas about tragedies found new popularity in the Renaissance period, which is why Shakespeare's plays, for example, borrow so heavily from them. Indeed, many if not all of Shakespeare's tragedies rely upon Aristotle's catharsis for their emotional impact. We pity Romeo and Juliet, for example, because their love is fated to end with their tragic, needless deaths. We fear Macbeth for his escalating brutality. Othello we pity for his blindness to the machiavellian Iago's malignity. And for King Lear we might feel both pity and fear. We pity the lonely, psychologically fraught state to which he is reduced, and we fear that he might die a desperate madman's death, shouting futilely into the storm.

The concept of catharsis in Aristotle's Poetics is based on a phrase at the end of his famous definition of tragedy. He states that

Tragedy . . . effects by means of fear and pity the catharsis of the pathemata.

The term catharsis in ancient Greek means some form of purification or purgation. The pathemata are emotions in their etymological sense of internal states produced by external impetuses. They are referred to in the genitive case, which, in this sentence, means that we have the sense of the emotions being purged (i.e., the audience being rid of a specific emotion) or the emotions being purified in the sense of being made more pure or improved. The medical sense of the word would suggest purgation and the religious sense either purgation or purification.

In the Poetics, what does Aristotle Mean by catharsis?

In medicine, a purgative is something that rids our bodies of something unpleasant. Laxatives, for example, evacuate the bowels when some poor unfortunate individual suffers from constipation.

For Aristotle in the Poetics, catharsis has a similar effect upon the emotions, especially fear and pity. These are very powerful emotions that cannot stay bottled up inside us for very long without causing significant psychological damage. It is essential, therefore, that we find some way to release them so that they can no longer torment our minds.

One of the best ways to achieve catharsis, according to Aristotle, is by watching a tragic play. Tragedies are very useful in this regard as they arouse feelings of pity and fear. Those feelings, no longer bottled up inside us and doing harm, are directed outward towards the characters on the stage, such as Oedipus or Antigone. Thus our souls are purged of these potentially destructive emotions and are no longer out of balance.

Catharsis, as Aristotle conceives it, is of immense therapeutic value. Once we've achieved the purging of fear and pity, we immediately feel a whole lot better. At the end of a tragic play, we should feel a sense of relief and satisfaction that those destructive emotions are no longer inside of us, ready to cause us considerable harm.

What is the significance of "katharsis" in Aristotle's Poetics?

Catharsis—an alternative spelling of the same word—plays a crucial role in Aristotle's Poetics. For Aristotle, the whole purpose of tragedy is to arouse pity and fear in the audience, and this process, akin to purgation in medicine, is what he calls catharsis. If a specific tragedy is unable to affect such a purgation, an emotional purification, if you will, then according to Aristotle it doesn't really count as tragedy in the truest sense.

Aristotle doesn't look upon tragedy as some kind of entertainment. On the contrary, it has an elevated role in transforming the individual spectator, broadening their whole outlook on life through an imaginative identification with a sympathetic protagonist. In that sense, tragic drama has a moral function. Moreover, it is didactic, that is to say it teaches something to the audience. But the moral lessons conveyed will not fully be learned unless there takes place within the spectator the kind of radical purification of emotions that catharsis entails.

What is the significance of "katharsis" in Aristotle's Poetics?

Interpretation of the phrase "katharsis of the pathemata" in Aristotle's Poetics has been disputed by scholars since the sixteenth century. The term katharsis in Greek has a sense of purgation or purification. Pathemata means emotions, but in the etymological rather than  modern sense, i.e. that they are something suffered or experienced by the person enduring them.

One common interpretation is medical, with the sens eof purgation, Purgatives, which make people vomit, were used in Greek medicine to rid the body of poisons or imbalances. On this reading, Aristotle is arguing that by watching imitation of emotions, we acheive something like apatheia by ridding ourself of excessive emotions.

Another reading is "making the emotions more pure", i.e. training people to have correct emotional responses.

What is meant by the “catharsis of emotions" in Aristotle's Poetics?

Perhaps the single phrase most often quoted in scholarly studies of Aristotle's Poetics is:

... through fear and pity affecting the catharsis of such pathemata ...

The use of the terms catharsis and "pathemata" are both somewhat unclear. The ;term "pathemata" is close to the English etymological sense of "emotion" in the sense of suggesting an internal state motivated by the operation of an external force. It could equally well be translated by "sufferings" in the sense of "things suffered" as opposed to "things done". Catharsis in Greek can be used medically to refer to purgation (e.g. vomiting to remove poisons) but it also has medical senses. The genitive is grammatically ambiguous as well, as it can mean either "making the pathemata more pure" or "purging emotions" in the sense of eliminating them or no longer feeling that specific response to something suffered.