Definition of tragedy and its parts

Chapter 6 delivers the formal definition: tragedy is an imitation of an action that is serious, complete, and of a certain magnitude; in language embellished with each kind of artistic ornament, the several kinds being found in separate parts of the play; in dramatic form, not narrative; through pity and fear accomplishing the catharsis of such emotions. Each term in the definition carries weight that the subsequent chapters will unpack.

From the definition, Aristotle derives the six parts of tragedy. Since tragic imitation requires agents, it must have: (1) Plot — the arrangement of the incidents; (2) Character — the moral qualities of the agents; (3) Thought — what the agents say in argument; (4) Diction — the verbal expression; (5) Song — the chief embellishment; (6) Spectacle — the visual apparatus. These six parts are ordered by importance, not by frequency. Spectacle is last because it is least artistic and least connected to the essence of poetry; the power of tragedy is felt even without performance.

The chapter insists, with unusual rhetorical force, that plot is the soul of tragedy. Tragedy imitates not men as such but an action and life — and life consists in action, not in a quality of being. Men are happy or unhappy by what they do. Therefore tragedy must be organised around action, and the structure of the action is primary. Character exists for the sake of action, not action for the sake of revealing character. A tragedy without character could still be a tragedy; a tragedy without plot could not. This is the most insisted-upon doctrine in the Poetics and the one from which everything else in the treatise follows.