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.