

"You don't know what it has been like, I assure you, being the only sane man in this madhouse!!" From the moment he says "Oh, yes! A ghost of a Ghost! Totally unbelievable and against all common sense, in the best operatic tradition!" he is doomed to an inexorable slide into insanity. But there is no escaping the fact that the final act is being played out, onstage, at the Opera House, and single exclamation marks begin to creep in the moment Walter Plinge, as the good ghost, appears on stage to confront him. He can even explain why he really, really, hates opera as an art-form while resorting to no exclamation marks whatsoever.


He behaves in a perfectly rational way for an unmasked criminal, taking Agnes hostage and using her as a bargaining tool to secure his freedom along with the stolen money. At first rational, explaining his actions and motivations and looking for a way to escape, there are no exclamation marks at all. There is a practical demonstration of this in the final act of the Opera in Maskerade, when Salzella is unmasked as the malevolent opera ghost. The basic idea is that a person's sanity is inversely proportional to the number of exclamation marks they use! There are a few mentions of multiple exclamation marks in the books and by Terry Pratchett himself, so it appears this is something he feels fairly strongly about.
