In all of Lemony Snicket's books there are a lot of references to the number 13! I mean, just look at his name! 13 letters! And a lot of the titles, such as 'The Wide Window' also have 13 letters. Of course, you can't forget that there will be 13 books in all, and each with 13 chapters. Now, I may just be talking nonsense, but since all the books are pretty depressing I dougt it is coincedence.