Everything you need to understand or teach Interesting Times by Terry Pratchett.
Oppression of the masses leads into the larger theme of social values. The moral principles of the Agateans are compared to those of the Morporkians.
Cohen and his Silver Horde—a group of sixty elderly barbarians and one elderly former teacher—make an excellent counterpoint to the Agateans. Saveloy's role is to civilize the Horde so that they can overthrow the Empire in an Agatean fashion. The barbarians find good manners and politeness chaffing and difficult, not to mention incomprehensible.
As part of his training, Cohen is instructed by Saveloy to buy an apple from a merchant, a task that he performs grudgingly. When the merchant calls him "venerable," Cohen beats the cart owner and steals his money. Pratchett here is underlining the hypocrisy of barbarian ethics. Cohen pays for the apple with one hand, while robbing the merchant with the other hand. It is questionable...