Concept:
Catharsis is a central concept in Western classical tragedy, describing the emotional effect a play should have on its audience.
Step 1: Identifying the philosopher and the theory.
The theory of Catharsis was propounded by the Greek philosopher Aristotle in his work Poetics. Aristotle argued that tragedy, by evoking "pity and fear," aims to bring about a purgation or "cleansing" of these emotions in the audience. This was largely a response to his teacher Plato, who believed that theatre was dangerous because it stirred up unruly emotions. Aristotle believed that by experiencing these emotions in a controlled theatrical environment, the audience achieved emotional balance.