Cinema is my greatest and most-consuming (pop) cultural love. But it was not my first. That "honor" falls to classical music. I love it when the two bleed into one another. Usually, that's when a filmmaker (like Tarkovsky or Singh or Wes Anderson) uses a piece of classical music directly. But sometimes, it's even more fun than that.
First, listen to the first fifteen seconds of this. (Actually listen to the whole thing, because it's great. But listen to at least the first fifteen seconds):
Then, listen to this. (Again, the opening will make the point, but the whole thing's great):
Also, just to be clear, this is an observation, not a criticism. Classical composers have been doing this sort of things for years, and Horner usually does a pretty good job of re-imagining/re-shaping/re-invigorating the stuff he finds in other places. (He doesn't do anywhere near as good a job of re-cycling his own work, interestingly.)
Along those lines, here's a fascinating piece on why he might be borrowing the particular themes he does. It's called "Willow: Between Quotes," and it's great:
Czech, Bulgarian, Norwegian, Russian, German, Hungarian… those are the origins of James Horner's quotes in Willow. He deploys all his knowledge of European music. At the same time, the composer's talent is to also propose a score that perfectly fits the pictures and that extends the musical legacy, through which his writing has developed, because of quotes guaranteeing a progression of harmonies and a respect of the authors' prime meaning.