Exactly right, but actually books are better than that: they're not just "really long movies", they're blueprints for your mind to create its own, personalized movies, with an unparalleled economy of information.
For example, this opening paragraph from
2001, A Space Odyssey:
This short paragraph essentially sums up the entire opening sequence of the
2001, A Space Odyssey movie before the monkeys start fighting. In only 406 characters, it sets the stage for the prehistoric bit of the story.
But best of all, your mind automatically makes up the missing details: the dry savanna, the heat, the stale air, the stench of decaying meat, the proto-human creatures watching one another, ready to fight and kill over anything to eat, the ominous silence... Thanks to your own imagination, those mere 406 characters are enough to open a huge window to our distant past and let in a whoosh of prehistoric air, all that in 10 seconds and in the comfort of your own living room.
And the scene you're contemplating is yours. We all imagine something else with words, nobody can imagine the same things you do. As a result, the movie you get out of a book is your very own, the best it can be, because you're the director.
The problem for me is when I read a book, then watch a movie based on it: as much as I loved the
2001 movie, and as much as I loved Kubrik's interpretation of the
2001 book, his vision of the book destroyed mine. I almost thought "oh, so that's what it looks like" and was almost disappointed at the realism of it all, because my own imagined movie was so much more dazzling and lively. I had the same disappointment with
The Fountainhead,
Blade Runner,
The Bicentennial Man,
Dune,
Brazil and countless other movies that I loved, but somehow trivialized and "flattened" my memory of the books they're based on.
I also have the same problem when reading a book after seeing the movie: my memories of the movie would involuntarily corral and entrap my imagination, making the book less enjoyable as a result.
That's the reason why I tend to avoid watching a movie based on a book I read, and if I did watch the movie, I'll wait as long as possible to read the corresponding book. It's a bit of dilemma of course with great movies based on great books
