I am not a Librarian (that requires a degree in library science which I don’t have) but I have worked in libraries and have friends who still do. I can’t imagine “you shouldn’t read that” would ever be the response.
Patron: I found this old book full of weird letters.
Librarian: Please don’t remove that from the reference section. Bring in your own notebook or buy a copier card if you would like to reproduce the eldritch symbols.
Darn kids always trying to make off with the reference books! No you can’t check that out.
Patron: I found this old book full of weird letters.
Librarian: Do you have a pass to be in the Special Collections stacks?
I worked in Special Collections for a summer taking inventory. There was some weird stuff in there. I suspected some of the books were in there not because they were rare but because they were sacreligious and/or had naughty pictures.
Special Collections is separate from Rare Books, at least at our library. Rare Books are on locked shelves behind layers of metal and glass, and they do not come out, ever, unless personally extracted by a full Librarian. Wearing gloves. And it stays in the librarian’s hand until locked up in a case again. Nobody else lays a finger on them.
Special Collections, anyone can look at a book but they have to request them and have library staff fetch them. Like behind-the-counter drugs. So an ordinary person cannot wander the stacks looking for weird books. If someone’s back there just browsing, it’s probably a security breach.
Patron: I found this old book full of weird letters.
Librarian: Does it have a barcode and a call number? If it’s not in the system, it’s not our problem.
People have been known to leave books in libraries hoping that we will confusedly decide it is a library book and keep it on the shelf. Usually professors wanting the textbook they wrote to be considered more valuable than it is, but I can imagine a crank doing this with a mystical-looking book.
Libraries are not actually as pleased as you might imagine to be ‘given’ random books.
Patron: I found this old book full of weird letters.
Librarian: Hmm, that language looks like [X]. You can find dictionaries filed under [Y].
This assumes you found the book somewhere other than the library and brought it in for help. A Librarian would certainly take a stab at identifying the language, but you’d have to hire someone for a special project if you wanted them to actually translate it for you.
Patron: I found this old book full of weird symbols and diagrams.
Librarian: Oh, that must have been misfiled! Alchemy goes under QD. Stacks, fourth floor.
Yes, we had an alchemy section. Yes, the library of congress classification files alchemy as a subset of chemistry. See also BF1000+ for the Parapsychology category which includes psychic research, ghosts, and aliens.
Patron: I found this old book full of weird symbols that keep pulsing and changing.
Do you really think we’d be more likely to tell you NOT to read a book? We love books! We’d be first in line to lose our SAN points.
One of these days Magical Diary needs a Librarian.