"And I don't want my files messed up or placed out of order. They're in a special order that makes sense only to me." (9.178)
Let's hear about this whole filing cabinet business from Mrs. Frankweiler herself, shall we? When we start reading From the Mixed-Up Files of Mrs. Basil E. Frankweiler, the title isn't exactly clear. After all, this is a story about Claudia and Jamie Kinkaid, two kids who are running away. What does this have to do with some lady with a weird name and her mixed-up files? Who even cares?
Even though things are a little mixed up in the book, they all come to light in the end. So maybe it would have been better if we knew more about Mrs. Frankweiler from the beginning, or if the reader was privy to the whole Michelangelo secret. Maybe it would have helped to know who Saxonberg was and whether he knew the Kinkaid children. But we found out everything we needed to know by the end, right?
Maybe, in the same way that Mrs. Frankweiler's files are all mixed up, the book is a little scrambled or mysterious, too. Mrs. Frankweiler keeps all her files organized in a way that only she can understand, because like Claudia, she wants to keep secrets to herself. So even though to an outside observer, those files are pretty confusing, she'll always know what's going on.
Like the files, everything should make sense in the end. Everything is in a special order, and each and every single secret is revealed to the reader by the end. So just sit tight and let the story take you where it will.