Catharsis

taken from wiki:

The term in drama refers to a sudden emotional climax that evokes overwhelming feelings of great sorrow, pity, laughter or any other extreme change in emotion, resulting in restoration, renewal and revitalization in members of the audience.

Using the term "catharsis" to refer to a form of emotional cleansing was first done by the Greek philosopher Aristotle in his work Poetics. It refers to the sensation, or literary effect, that would ideally overcome an audience upon finishing watching a tragedy (a release of pent-up emotion or energy). In his previous works, he used the term in its medical sense (usually referring to the evacuation of the "katamenia", the menstrual fluid or other reproductive material). Because of this, F. L. Lucas maintains that catharsis cannot be properly translated as purification or cleansing, but only as purgation. Since before Poetics catharsis was purely a medical term, Aristotle is employing it as a medical metaphor. "It is the human soul that is purged of its excessive passions." Lessing sidesteps the medical aspect of the issue and translates catharsis as a purification, an experience that brings pity and fear into their proper balance: "In real life, he explained, men are sometimes too much addicted to pity or fear, sometimes too little; tragedy brings them back to a virtuous and happy mean." Tragedy is then a corrective; through watching tragedy the audience learns how to feel these emotions at the proper levels. Some modern interpreters of the work infer that catharsis is pleasurable because audience members felt ekstasis (Greek: ἔκστασις)(ecstacy)(literally: astonishment, meaning: trance) from the fact that there existed those who could suffer a worse fate than them was to them a relief.[citation needed] Any translator attempting to interpret Aristotle's meaning of the term should take into account that Poetics is largely a response to Plato's claim that poetry encourages men to be hysterical and uncontrolled. In response to Plato, Aristotle maintains that poetry makes them less, not more, emotional, by giving a periodic and healthy outlet to their feelings.

In literary aesthetics, catharsis is developed by the conjunction of stereotyped characters and unique or surprising actions. Throughout a play we do not expect the nature of a character to change significantly, rather pre-existing elements are revealed in a relatively straight-forward way as the character is confronted with unique actions in time. This can be clearly seen in Oedipus Rex where King Oedipus is confronted with ever more outrageous actions until emptying generated by the death of his mother-wife and his act of self-blinding.

In contemporary aesthetics catharsis may also refer to any emptying of emotion experienced by an audience in relation to drama. This exstasis can be perceived in comedy, melodrama and most other dramatic forms. Deliberate attempts, on political or aesthetic bases, to subvert the structure of catharsis in theatre have occurred. For example, Bertolt Brecht viewed catharsis as a pap for the bourgeois theatre audience, and designed dramas which left significant emotions unresolved, as a way to force social action upon the audience. In Brecht's theory, the absence of a cathartic resolving action would require the audience to take political action in the real world in order to fill the emotional gap they experience. This technique can be seen as early as his agit-prop play The Measures Taken.

here's the full article: "Catharsis"