Define: Librarian

This from a review of This Book is Overdue by Marilyn Johson; from the NYT Book Review:

"They are people who struggle to bring the dead back to life. Johnson’s characters desperately care about half-forgotten brawlers, freedom fighters and canine celebrities. They are the guardians of all there is to know. It doesn’t matter whether they carry on their efforts in analog or digital format. For they are waging the holy battle to resurrect the entire world, over and over again, in its entirety — keeping every last tidbit safe and acid free."