CriticaLink | Aristotle: Poetics | Guide to Book XIX
All mental activities portrayed by the speeches of characters in the drama fall into the category of thought. Aristotle lists the logical and rhetorical exercises of proof and refutation, expressions of emotional states, and judgments as types of thought represented in tragedy. Aristotle cautions that speeches must not be used merely for exposition, to explain the plot to the audeince, but that the episodes should appear to unfold naturally, requiring no explanation from the actors. Here again, Aristotle stresses the integration of the different components of the tragic drama.
Aristotle's discussion of diction is brief and suggests that this component lies outside of the poet's art. Diction describes the way characters deliver their speeches. Experts in the art of oratory (or, in our own time, the director and dialogue coach) are more responsible for the success of this dimension of tragedy than the poet.