Books and cats. Cats and books. They go together like a hot dog and mustard. Well, no they don’t. And I don’t like mustard on my hot dogs anyway.
What I meant was that cats appear in a lot of books (and poems, songs, paintings and other forms of art, probably including architecture). They’re just so adorable and full of personality (I didn’t say “purr-sonality” — you’re welcome) that authors can’t resist them.