Open bookcase as diffuser?

I have a bookcase in the hallway and I was told by an internet buddy that the bookcase would work great as a diffuser if the bookcase had an open back? He did not elaborate(I don't think he knew why) and I am wondering why the bookcase needed an open back? If the bookcase is filled with books of different sizes and dimensions, why does the bookcase need to have an open back?

Does anyone use a bookcase this way?
It doesn't need an open back--it would be a very crude and unpredictable (not easily predictable, at least) diffusor either way, if you just do things at random. If you want to turn it into something along the lines of an RPG diffusor, get in touch and I'll email my plans for several RPG-style diffusors, which you could adapt to this bookcase project. You'd need books with depth ratios 1, 2, 4, and the 1 probably couldn't be a book but that's okay. If the bookcase is really deep, it will be easier to get the 1, 2, 4 depth relationships. I've never done it since I use real diffusors instead, but it could be done--if you learn what you should be trying for.
Listen to Tom, you don't want all the books spines standing out flush, but staggered instead. Needless to say glass doors would negate the whole idea.