I don't know if this is THE formula for creativity but it's certainly A formula for creativity. It comes from James Altucher, who writes blog posts and books that are very frank, sometimes to the point where you feel a little embarrassed for him--until you realize you have your own quota of humilating things that happened and the only difference is you don't write about them. Here's his creativity formula:
Take something new, find something old that relates to it. Mix them together. See what happens.
He cites Steven Pressfield's confession that he used The Bhavagad Gita as the basis of The Legend of Bagger Vance. Who knew?!
For the "old" Altucher suggests stories that have stood the test of time. That's something I mention in my screenwriting workshops, too. Don't feed your head with just the hot movies of the moment. At the very least, see the classic films and ones made in other countries, showing other cultures.
Then go back a long way more, to mythology, folk tales, fairy tales. If you're interested in writing horror, read the original versions of fairy tales, not the Disney versions. For instance, in the orginal version of Cinderella, the stepsisters are so determined to get their feet into that glass slipper that they hack off their toes and heels.
Find some stories that haven't been used so often. Skip Romeo and Juliet, for instance. It's served as the basis of West Side Story, The Lion King II (they used Hamlet for the first one), and many, many more.
Here are a few you can access at www.gutenberg.org:
Adventures of Huckleberry Finn
Grimm's Fairy Tales
The Children of Odin: The Book of Northern Myths
Gulliver's Travels
Dubliners
Roughing It
Heart of Darkness
The Illiad
The Awakening and Selected Short Stories by Kate Chopin
Of course most of these have been used as a source for films and novels but there's plenty of life left in all of them.
If you have a new idea, how could mixing it with one or more of these old stories enrich it?
(You should also feed your head with my book, Creativity Now, published by Pearson and available from Amazon or your other favorite bookseller. Why not order it from your local independent bookshop? Let's keep the indies in business!)