Buck-Beaver said:
I'm not so sure...(the Jim Henson Company) specifically asked them to come up with something in the same vein as Labyrinth and the Dark Crystal, but you're right it's a story as old as time.
I wasn't exactly sure what you were trying to say here, but I respect your postings on this site and would probably agree with you under different circumstances. What I was saying, in response to someone who'd earlier mentioned that the Mirrormask plot sounded like a retread of Alice in Wonderland, is that it was doubtful that the Henson company set out, intentionally or otherwise, to borrow ideas from Alice or any other classic literature for the purpose of making this film.
However, I pointed out that, in several volumes of research on the subject, it's proven that all great works of fiction can be inevitably traced back to age-old, classic themes (read Joseph Campbell's "The Hero With A Thousand Faces" for further explanations). Unavoidably, common links are often found in these works, but that does not mean or prove that they are intentional rip-offs. Obviously such plagiarism does exist, but it's not in the Henson company's nature to employ such underhanded tactics.
So getting back to your quote, you're right, the plot of Mirrormask does harken back to a theme that's as old as time. I just don't see what your point was regarding the Henson Company telling Gaiman to write Mirrormask's story with Labyrinth and The Dark Crystal in mind. Are you saying that the Henson's are, in a sense, plagiarizing themselves? I don't think that's technically possible, and I just can't see how that can be compared to borrowing plot ideas from classic literature.
Bascially, Mirrormask's plot, unless otherwise specified by Gaiman or the Henson's, is a work of their own, free of any blatant outside influence from classic folklore. Were it indeed inspired by Labyrinth or Crystal is irrelevant to the argument, since they are also the Henson's creations, free of outside literary influence.