"“I can tell you anything you need to know,” said Vimes. “Yes, Your Grace, but that is not how an inquiry works. I must act completely independently. Quis custodiet ipsos custodes? Your Grace.” “I know that one,” said Vimes. “Who watches the watchmen? Me, Mr. Pessimal.” “Ah, but who watches you, Your Grace?” said the inspector with a brief smile. “I do that, too. All the time,” said Vimes. “Believe me.” (p. 17)"