On the Other Hand...

On the other hand, where does appropriation stop? When Perelman wrote (or didn't write) "Captain Synchronicity, Block That Kick!" wasn't he in fact just appropriating "words" that were already in the dictionary? And weren't those words merely rearrangements of previously-extant "letters"?

Couldn't the same thing be said of the writings of, say, Levi-Strauss?