Librarians do not like conflict. Books about things the librarian feels are confusing can be placed together in an area and more books can be written about them to explain what they really mean. Books about other books are the finest books in the world. Second-hand book store owners are Fathers. They try to arrange the books neatly, though perhaps not rigorously.
Books fall over.
People read and do not replace correctly. Books leave the store and never return. Library books are returned and eventually forgotten. Bought books are kept and read again.