Biting My Tongue (sort of)

I am very picky about my music. It may look unorganized, but everything has it's place. I've got it divided into piles according to voice part and style. The frequently used books are on the top, less frequently used gravitate towards the bottom. Rarely used music is in a separate place. This system has become a necessity ever since my large, beautiful shelf with all the cubby holes went into storage.

Last night there was an open house of sorts for my father-in-laws birthday. (Happy Birthday!) When I came up this morning, my music was a mess!

My nicely organized and neat piles were askew. The bass music was with the classical books. The tenor books were stacked with the soprano books. Several books were temporarily MIA, including my beloved mezzo books.

Why do people assume that just because it's there they can mess with it? And why do they assume that because it's in piles it doesn't matter where they put it back?