A successful adaptation does not follow the exact path of the novel, nor does it stick faithfully to the text. Rather it finds the essence of the book and transforms that into a story that will work in the medium of film. Whereas authors are at liberty to leisurely explore a character's internal thoughts and motivations, screenwriters must express these things visually or through dialogue � or, in Annie Hall, with Woody Allen's brilliant use of subtitles to reveal the thoughts of the characters at their first meeting. Thus, adaptations present the complicated challenge of transforming the internal into something visual.

The recent feature film version of Pride and Prejudice tries to stick so closely to the body of the text that it fails to do the novel justice. By contrast, in another Jane Austen adaptation, Sense and Sensibility, screenwriter Emma Thompson has cut major characters, changed entire scenes, and even created from scratch everything that occurs in the first act when Edward and Elinor first fall in love. And it won the Academy Award for Best Adapted Screenplay. Making these changes allowed the film to perfectly capture the spirit of the novel, which is the primary objective in adapting anything.

In her commentary to the film (on the DVD), Thompson tells a story of one person who told her how much the "atlas scene" in the first act (when Edward and Elinor use Margaret's love of her atlas to coax her out of hiding) reminded her of that scene in the book � and that scene doesn't actually exist in the book! That story demonstrates how much a work must sometimes be altered in order to be successful in the medium of film, and that by changing situations to suit the medium a novel can sometimes be more faithfully represented than if the writer had stuck precisely to the text. Thompson's adaptation honours Austen's work, not to the letter but, more importantly, by bringing its essence to life on the screen.

Of course, it is possible to make a successful adaptation that does closely mirror the book on which its based. 'Harry Potter' is a wonderful example of this since screenwriter Steve Kloves wrote an incredibly faithful adaptation.

The film version of Harry Potter and the Sorceror's Stone had a nearly impossible challenge before it � millions of fans eagerly awaited this first adaptation in the Potter series, knew the text extremely well, and had high expectations for the film. How could the screenwriter hope to satisfy them? Against all odds, he managed. And considering the criticisms of some that it followed the text too closely, it's interesting to note that the entire subplot involving Hagrid's dragen has been cut, to name just one example of the many changes and omissions which occurred between the novel and the film.

Peter Jackson's Lord of the Rings trilogy faced the same obstacle. How could anyone transform Tolkien's classic work into a cinematic masterpiece? Not only did Jackson succeed, but many would agree one of the major changes he made for the third film, The Return of the King, should have been made to the original text as well � the removal of all the final challenges the hobbits face when they return to the shire. This sequence goes on and on in the book after the ring has been destroyed and thus after the main story has finished. Therefore, even though this takes up close to 100 pages of text, Jackson wisely slashed it all from the film.

But how does one go about adapting a novel?

"Studios have begun to accept that the adapting process may involve even more work than writing an original, because the scriptwriter may have to change entire characters and story incidents to make the script work within a dramatic context. Sometimes this involves a considerable amount of time and work." Screen Adaptation: A Scriptwriting Handbook, page 4

Obviously, different screenwriters have different techniques. But the starting point does (and should) remain the same: what is the essence of the novel? Something drew the writer to this particular text, and made him or her want to take the time to adapt it. What was it? What's the heart of this story that the writer wants to express in a film? Then it's necessary to go back through the text and cut anything not related to this central theme. Unnecessary scenes, characters, and subplots must be removed, particularly when adapting from longer novels. While these things may add to the enjoyment of the book, they slow down the pace of films and often detract from the central story.

Returning to the example of Sense and Sensibility, Thompson cut the beloved character of Lucy's sister. She provides several comic moments in the novel, but she's unnecessary to the heart of the story and therefore had to go. Likewise, in the novel there's an entire sequence in which Edward visits the Dashwoods at their new home. Thompson took the necessarily bits of dialogue from this and used them instead when she created the initial sequence of Edward and Elinor's first meeting and falling in love. Then she cut his visit entirely. Again, this omission makes the film stronger, not weaker.

By contrast, since Pride and Prejudice has tried to include everything, it suffers from a lack of character development and suspense. Situations get resolved too quickly, and certain characters, especially Wickham, get almost no screen time.

There are a few steps screenwriters can follow in order to help determine what should stay and what must go.

First, figure out who the main character is. Sometimes this is obvious, as in the case of Harry Potter. Other times it's less so, as in the recent comic book adaptation of Fantastic Four. I feel that's actually one of the major weaknesses of this film in that it didn't selected a main character. Some may argue that it's Reed Richards, aka Mr. Fantastic, but the story follows all four characters fairly evenly without taking a strong point of view. By contrast, X-Men wisely chooses Wolverine as its main character, and even though the team is still in place, we follow most the action from Wolverine's perspective. It makes for a much stronger film.

Next, figure out what the main character wants and what's stopping him or her from getting it. In Sense and Sensibility, Elinor wants to be with Edward. That's made clear from the beginning. Her financial situation, his previous engagement to Lucy, and his family's objections all stand in her way. In this particular work, the subplot of Marianne is crucial because Marianne's character is the antithesis to Elinor's. One is the "sense," the other the "sensibility," and the film shows the path of both to finding love. Also, similar obstacles lie in Marianne's love for Willoughby, and the resolution of that relationship builds the suspense in the audience's expectations for whether Elinor and Edward will finally be allowed to be together themselves.

Once the main character's goal, and the obstacles preventing it, are clear in the screenwriter's mind it's easier to figure out what must be included in the script and what must get cut.

Finally, and perhaps most importantly, the writer must be clear on why he or she wants to tell this story. What is (s)he trying to say? This is the theme of the work, and again, anything not directly related to this theme has to go, no matter how wonderful it is in the book.

Anything can be adapted into a screenplay, ranging from a paragraph in a newspaper that sparks an idea, to a 1,000 page epic novel. The same basic principles apply to all of them. But, at the end of the day, each screenwriter must discover what works in that particular case, for that particular script. Unfortunately, there are no hard and fast rules that will guarentee a successful adaptation. But, on the bright side, there are many excellent adaptations you can enjoy watching and learn from.