Because it is library-fortress and protected absolutely. Its rules and wards are countless... And it is guarded by armed monks, and you must have written permission to enter its Inner Ward, and you may only remain for tenday at one time. There is even great mythal, which is ... hm. Imagine persistent magical field, so incandescently powerful it permanently alters Weave and how it functions.

[ and so, of course, she is so hungry to see it herself. ]

I do not think even you could break in unnoticed.