Thar is a very interesting question, and potentially a very challenging one, given the sheer diversity of characters, settings, themes and stories that comprise the Chronicles. It's hard enough to find many unifying threads that span the individual books in and of themselves, never mind the whole series.

But I guess perhaps the simplest answer, and maybe the most boring answer, is in fact the correct answer in this case - Aslan.

From a thematic perspective it's perhaps obvious why Aslan is important, but from a screenwriting perspective, as a potential "north star" to help orient your script writing process and to act as a handy "rule of thumb" for knowing what to prioritise at any given point, Aslan works well as a North Star precisely because he's hardly in the stories.

He is without doubt the main character, the most famous character, and yet in terms of physical presence he is hardly in any of the books.

Therefore I guess if I was a screenwriter I would be continually asking myself whether my adaptations, changes and amendments help in any way to build up the other characters relationship with Aslan, or whether the world building elements of the film serve to tell us anything about the way the Narnians experience and understand Aslan.

Perhaps there's more depth to it than that, but that would be my initial first answer of the top of my head... particularly given that I fully expect Greta Gerwig to adapt LWW with a firm focus on Lucy, and rooted in her own personal experiences of growing up in a Catholic school and her overall relationship with god, Aslan seems like a good symbolic north star for her to keep her focus within that personal journey as well.

I think Rose-Tree Dryad's and Icarus's suggestions make sense, but I don't feel comfortable speculating on what Gerwig's "guiding star" is going to be for Narnia. The examples she gives with those two other movies sound pretty personal and specific to her, so I wouldn't expect them to be just what I think is the main theme of the book series.

Also, while the interview makes me interested to learn Gerwig's guiding star for Narnia, I don't believe it'll actually be the main thing I or any other viewer is going to take away from the movies. You see, with the examples she gives, I can see how the things she mentions are in or influenced the stories, but I really wouldn't have guessed she saw those as her "guiding star" while telling them. (I'm going to be free with spoilers since Gerwig strikes me as being free with spoilers in the interview.) There's a scene at the tail end of Little Women in which the main character who is an author agrees to give the heroine of her novel a successful romance despite her inclinations but insists on keeping the copyright and it's a cool scene but it's actually in an epilogue of sorts that's somewhat detached from the main body of the story. It's true that at the beginning of the story the character is an author who has to make a lot of compromises to get anything published and at the end, she's in a bit more of a position of power or, at least, has written in something she believes in more. But I'm not sure how many viewers actually see the movie as building up that scene. You could just as easily say it's leading up to the scene afterwards, the one of the heroine finally seeing her book bound and printed. (Prior to that her work had just been published serially in magazines, etc.) You could just as easily say the heart of the movie is an earlier scene where she frets that her book can never be great literature because of its subject matter and another character suggests she and society need to change their idea of what constitutes great literature. And there are plenty of other scenes that could be reasonably called the heart of the movie which don't even have to do with writing! And Barbie does have a character who is a big fan of the Barbie franchise and another character who thinks it's a bad influence on society. But the movie doesn't really explore either of those positions in any depth. It just has characters who repeat the party lines and then uses that as a jumping off point to move on to other topics. 

I don't mean any of that as a criticism of Gerwig's Little Women or Barbie movies! (Well...if I'm being honest, I'd say what I was talking about with Barbie is characteristic of what I see as a problem with it: There are so many issues it wants to include that it doesn't have time to delve into most of them and to my way of thinking, comes across as more pretentious than insightful. But that one example by itself doesn't have to ruin the movie.) I just don't think what she considers the thematic backbone of her Narnia movies is going to be what strikes me as their backbone when I watch them. And that's fine as long as the movies are good. Now I actually kind of want to avoid learning what her guiding star is going to be until after I watch them, so it doesn't color my first viewing experience.  

Posted by: @rose

For me, the gold thread that runs through all of The Chronicles of Narnia is the "longing for that unnameable something," the ineffable desire for one's true home that haunts us all our lives until we finally understand what it means, which the Friends of Narnia discover at last in Aslan's Country at the end of the series. I hope one day we see an interview with Gerwig where she mentions sehnsucht or Lewis's concept of joy!

Took the words out of my mouth! 🙂 If I had to boil down what Narnia is about in a single word, it would be sehnsucht for sure. Some books deal with it more explicitly than others (VDT, in particular, tackles it the most head on), but it never feels very far from the text. The land of Narnia itself - the dark forests ringing with dwarf's hammers, the mysterious eastern sea, midnight dances under the stars, abandoned castle ruins the characters used to live in etc. - feels designed to evoke a sense of mysterious longing.

Gerwig came tantalizingly close to referencing Lewis's concept of joy in the Time Magazine article. The sentence right after the one she paraphrased from On Three Ways of Writing for Children is "This is a special kind of longing". In isolation, that sentence won't take you all the way to Lewis's more developed thoughts on joy of course, but it's encouraging to know that her reading is taking her in the ballpark. A re-enchantment of the world isn't sehnsucht per se, but it's close. Certainly closer to the mark than I've heard any of the previous Narnia directors speak. *Gandalf voice* And that's an encouraging thought.