More useful questions from students came after class today. One required clarification of the Aristotle's treatment of two types of drama: Tragedy and Comedy.
Remember that Tragedy is imitation of actions of men or women that are better than ourselves, and Comedy is imitation of actions of men or women that are worse than ourselves.
Tragedy (in Aristotle's Dramatic sense) is not a synonym for "sadness" nor is Comedy (in Aristotle's Dramatic sense) a synonym for humour. Tragedy can contain humour and Comedy can express sadness.