I read a book a decade ago and struggle with it. I read it again now and find it astonishingly thought-provoking. How do you explain this? It seems I bring something different to the book on the second reading: concepts, experiences and knowledge which I lacked at the time of the first reading. But what role does the book play? It seems obvious to me that this can only be explained in terms of the interaction of two sets of properties and powers: mine and those of the book itself. I have changed in the aforementioned decade but the book has not. The causal role of the latter is not trivial and understanding it opens up really interesting questions about the ontology of books. Books can change us but, as we change, so too does what we bring to books as we engage with them.