Katharsis as the ancient Greeks defined it, meant cleansing or purification. In today's screenwriting world, using Catharsis properly describes a high level of process achieved by the writer, and is used by the industry as an adjunct to grade T.V. and film scripts for potential production. In their bag of tricks, formally known as proficiency, students of the screenwriting craft learn, real people characterization, the importance of dialogue and less is more, plots that keep your audience on the edge of their seats, and Sir Alfred Hitchcock's mastery of suspense.
So, what is it, and why does a screenwriter need to master the use of Catharsis in his/her script?
Here's one definition. "Catharsis is the process of releasing, and thereby providing relief from, strong or repressed emotions." Originally used in Greek tragedy, to recall emotions of fear and pity and then releasing them to the universe, used in a script, this event usually happens in Act 3. The ending of the show built from the previous 2 Acts, in a traditional 3 Act format. In cinematic terms, it's the feeling left with the audience once the protagonist completes his journey and resolves the issues that have tormented him. It's a powerful ending statement that impacts all of us, be it in the theatre or even reading the script.
What you feel may have nothing to do with you personally. When the picture fades to black or the closing credits roll, a simpatico moment occurs between you and the protagonist. You can feel their relief and that feeling makes for good screenwriting. Sometimes the effect is, so dramatic, it can change someone's life. If so, you have just crafted an incredible screenplay. Good enough to allow you to ask for a single frame credit as big and with onscreen time the same as the director.
One of my favorite movies and one with a big-time Catharsis ending is The Dead Poets Society with Robin Williams. In another life, I was part of the production crew on Good Will Hunting and got to see him perform up close and personal. Here's a recap of the tragic story of Mr. Keating (Robin Williams) a teacher at an all-boys private school cursed with old boy's tradition, and reluctant to change. Enter Mr. Keating a man of intrigue and with some effort a man of inspiration changing boys to young men in the process. His way of teaching did not sit well with the school's authoritative rules. He was considered a loose cannon, sure to destroy the good name of this ivy walled institution. Because he was different and an outsider to these hallowed halls of learning, he was made the fall guy for a student's suicide.
Students were coerced into signing a document blaming Keating for the suicide death of a classmate. In his classroom, they were forced to watch him gather his personal things under the austere gaze of the headmaster. Justice would not be served on this day. Or would it?
In defiance of the headmaster, as Keating is about to leave the classroom, one by one the students stand on the tops of their desks to honor the man who had taught them so much about life. Using a line Keating had taught them from a Walt Whitman poem "Oh Captain My Captain" each student repeats the line "Oh Captain My Captain" despite the protestation of the headmaster. It was their way to say goodbye. Pausing at the doorway on his way out, Keating's reply to the boys honoring him is a simple but powerful two lines. He says, "Thank you, boys. Thank you." and leaves. If you are not touched by this emotional Catharsis moment, you probably have no soul. It's that powerful. Check out The Dead Poet's Society for yourself. It's a much better description of Catharsis than the words I have written here.