Catharsis

Catharsis (from Greek κάθαρσις katharsis meaning "purification" or "cleansing") is the purification and purgation of emotions—especially pity and fear—through art or any extreme change in emotion that results in renewal and restoration. It is a metaphor originally used by Aristotle in the Poetics, comparing the effects of tragedy on the mind of spectator to the effect of a cathartic on the body.