Exactly. [ IShe has the slightly fond, proud tone of a teacher who's gotten a correct answer back from a student. ] I had much the same thought. It's common for nobles and the like to have such passages installed in their personal quarters, so it seemed strange that one would be here, but...

[ She lifts the lantern a little more, spilling light over the dusty bookshelves. This part of the library is pretty out of the way, sure, but depending on where the passage leads... ]

Perhaps this is a case of accessibility trumping privacy? Could this be a method of traversing the school at speed without being detected?