Effect of Different "Books"

I think that the "books" inside another book is basically the same as breaking the book into parts. And splitting books into parts is useful in many ways. First, it probably helped the author keep track of what he was writing- I know I always break my writing into different parts so I don't have to look at it as a whole, which can be overwhelming. Also, it gives the story a chance to take on a new direction. When a new part begins, anything can happen, such as a change in the focus, a change in the setting, a lapse in time, and even the narrator can change. It gives you a chance to see the story from a new perspective and maybe skip over unneeded information. It also helps organize the process of a book, and the way it is organized can tell you about the story and the style of writing.