"Bibliotheken rechnen sich nicht, aber sie zahlen sich aus" translates roughly to "libraries do not pay for themselves, but they do pay off."
I learned this when I wandered into the beautiful Rostock stadtbibliothek, aka the Rostock city library.
In the city park, we came across another special library. You can take a book. You can give a book. You can borrow a book.
Yours in appreciating libraries at every turn,