Heraclitus, the Greek philosopher who lived during 5th century BC, said –
A man can never step into the same river twice, for it’s not the same river and he’s not the same man.
I would like to posit that Heraclitus’ observation applies to books also. Unlike the river, a book doesn’t change much but the reader does.
When you reread a book, what you see and understand is very different from what you saw when you read it the first time. It’s true for the good books as well as the bad ones. In your second reading, you may realize that the book you initially thought as amazing wasn’t really so and vice versa.