If I wanted something that sounded like Copland I'd dig him up, prop 'em up on a chair and ask him to write it for me!

Paradox here - because it's actually very difficult to write (music or writing) in the style of someone else, and make a convincing job of it.

I think it's inevitable that when we create we use existing ingredients, especially our personal (conscious and unconscious) favourites. That's not to say that the end product isn't effectively original, as the memetic whole is much greater than the sum of parts. But to be truly original you'd have to have been raised on another planet orbiting another star. And even that may not be enough.