Gregory Maguire, author of the novel Wicked, takes a look at screenwriter Noel Langley’s early draft of the script for The Wizard of Oz:

The differences between this version and the final shooting script? Hardly a page escapes without crossed-out speeches and handwritten substitutions. Plot points abound that are later abandoned (the Wicked Witch of the West has a son named Bulbo?). Only a couple of scenes refer to singing, and none of the famous lyrics appear. What would become “Over the Rainbow,” which I call America’s unofficial national anthem, is referred to as “the Kansas song.”

What this draft achieves is the compression of choice elements from a best-selling, although rambling, children’s book. In the original novel, the Wicked Witch of the West dies on Page 155, but Dorothy doesn’t leave Oz until 100 pages on. If Langley stuffs in extraneous characters for ballast (a Kansas farmhand and his sweetheart among them), he also abbreviates the trajectory of the story so that the demise of the Wicked Witch of the West kick-starts Dorothy’s return to Kansas.

Adapting a book to film means figuring out which elements of the source material really belong on the big screen. It many cases, you end up dropping things not because they’re “un-cinematic,” but rather because they don’t help you tell the two-hour version of the story.

Sometimes, the choices you make feel better than the original:

The American author-illustrator Maurice Sendak believed that The Wizard of Oz film was a rare example of a movie that improves on the original book. I agree with him. Langley consolidates two good witches into one. He eliminates distracting sequences involving populations Dorothy encounters after the Wizard has left in his balloon —the china people (porcelain figures) and the Hammer-Heads (a hard-noggined race).

You’d have a harder time taking these liberties with a popular novel now. The Harry Potter films were faithful and tremendously successful, as was Twilight and The Hunger Games. Studios see this and take note.

Over the last ten years when I’ve been approached to adapt current best-sellers, one of the first concerns has been not angering authors and fans. That may be the smart choice financially, but it doesn’t always result in the best movie.

Had Langely been given this directive when adapting The Wizard of Oz, I doubt we’d remember the movie at all.