The book is set in a fictitious country whose claim to fame was the creation of that one sentence, you know about the lazy dog and the fox, and using all 26 letters? They have a statue and everything. Things go wrong as letters fall from the statue - and the town council decide that if the letter's missing from the statue, you can't use the letter upon penalty of banishment and/or death.
So the book becomes increasingly difficult to read towards the end, when there are only five letters remaining.
I think I strained something in some verbal part of my brain.