[[Oh man oh man headcanon based on what you just reblogged. My theory behind library/book collections being personified is that if they're well-loved and often-read/visited, that's how they come to be able to take a human form. Because the books themselves have enough life on their own, but the love and use of humans is what really brings them to life. So really famous libraries/collections would be personified for sure.]]
((That is basically my headcanon as well. Though perhaps replace "able" with something that implies more randomness. I don't think Athena chose to be human, it is just something that happened. I kinda dream that if Bentley and her get together, the Anhk-Morpork Library will wander in to her life in human form and cause drama between them. Because damn, that would be a sexy human library.))