The summer Christopher Nolan moved to Los Angeles, he drove there from Chicago with his younger brother Jonathan, and on the road Jonathan told him the story he was trying to write. A man who cannot form new memories is hunting the man who killed his wife. Christopher asked to turn it into a screenplay while Jonathan kept working on the story, and Jonathan said fine.
The brothers agreed that the story belonged inside the man's head. Told in order, the film would give every viewer the one thing the hero had lost, which is a memory of the scene before. Nolan's solution, which he said "took a while to come up with," was "to tell the story backwards so that it denied the audience the information that the protagonist is denied."
He had paid for the other method already. On his first feature, Following, he wrote the story in chronological order and rearranged it afterward, and the rewriting it demanded was heavy enough that, as he told a British Film Institute audience, he "never did it that way again." For Memento he wrote "from the first image that the audience would see to the last."
The first image is a Polaroid. A hand shakes it, and the photograph of a dead man fades. The picture slides back into the camera, and a bullet flies back up the barrel of a gun. From there the color scenes run in reverse order, and black-and-white scenes run forward between them until the two lines meet.
Memento reached American theaters in March 2001 and earned about $40 million worldwide and Oscar nominations for its screenplay and its editing.
Nolan found his answer at the end of the story. He started there and wrote his way back toward the beginning.
The Why
That move has a name, Inversion: turn a problem around and attack it from the far end. One version starts from the finished result and asks what had to happen just before it. The other starts from the outcome you fear most and asks what would cause it. Asking how to tell the story could have sent Nolan anywhere. Asking what the audience must be kept from knowing had one answer, and it was everything the hero had forgotten.
The idea travels under a mathematician's name. In 1916 Edward Van Vleck wrote in the Bulletin of the American Mathematical Society that Carl Gustav Jacob Jacobi "is said to have inculcated upon his students the dictum: Man muss immer umkehren," one must always invert, and that Jacobi built his theory of elliptic functions "by turning the elliptic integral inside out." In 2024 Michael Molinsky, writing for the Mathematical Association of America, could find no trace of the saying before 1916, so the line may be classroom legend.
The investor Charlie Munger carried it into ordinary life. On June 13, 1986, he delivered an upside-down commencement speech at the Harvard School, a boys' school in Los Angeles. The talk-show host Johnny Carson, he told the graduates, had once offered a class prescriptions for sure misery, and Munger added four of his own and opened with "First, be unreliable." He credited "the great algebraist, Jacobi," with repeating one phrase, "Invert, always invert," and he closed with a toast: "Gentlemen, may each of you rise high by spending each day of a long life aiming low."
The speech worked because misery fits on a checklist. A graduate could hold "be unreliable" up against his own week and get an answer. Seneca ran the same move on fear when he told his friend Lucilius to "assume that what you fear may happen will certainly happen," a Stoic exercise known as premeditatio malorum.
Creative work runs forward by default. A novelist starts on page one and a designer starts with the ideal user, and both reach the ending last, long after most choices have been made on its behalf. Inversion sends you to the one place in your project you have never stood.
The How
Five steps. Each one reverses a default creative instinct.
- Start with the opposite of your goal. Write your goal at the top of a page, write its opposite under it, and list everything that would produce the opposite. Make each item specific enough to find in the work. The crime novelist Elmore Leonard ran this on boredom. His ten rules of writing, printed in The New York Times in July 2001, read as a list of ways to lose a reader, from "Never open a book with weather" to the last: "Try to leave out the part that readers tend to skip." Each rule points at something a writer can find on the page and delete by lunchtime.
- Work backward from your desired endpoint. Write the final scene, image, or line first, concrete enough to film. Under it, write "What must be true one step earlier?" and answer it, then repeat until you reach the opening. Keep each link only if the link after it needs it. Edgar Allan Poe claimed he built "The Raven" this way. In his 1846 essay "The Philosophy of Composition," he said he wrote the climactic stanza before any other, so the poem had its beginning "at the end, where all works of art should begin." Poe admitted the essay was not meant as literal truth, though his editor Thomas Ollive Mabbott judged the stanza-first story may be true.
- Identify your constraints before you identify your freedoms. List what the project cannot do before you list what it could become: the budget, the running time, the words a young reader can read. The limits settle which possibilities exist. Bennett Cerf of Random House bet Theodor Geisel, who signed his books Dr. Seuss, $50 that he could not write a book using only fifty different words. Geisel kept charts and checklists of every word he used, added a rule of his own, one syllable per word with "anywhere" as the lone exception, and published Green Eggs and Ham in August 1960. He later claimed Cerf never paid.
- Question your assumptions by reversing them. List the rules your field treats as settled, write the reverse of each, and ask what the reversed rule would let you build. In 1971 Renzo Piano and Richard Rogers won a competition that drew 681 entries for a new arts center in Paris by reversing the habit of hiding a building's machinery. They hung the pipes, ducts, and escalators on the outside and color-coded them by job, blue for air, green for water, yellow for electricity, and red for moving people, which left the galleries inside open to rearrange. Le Monde called the Centre Pompidou "an architectural King Kong." Most of your reversals will fail, and the survivors show you which rules were habits.
- Build checkpoints that work backward. Put the finish date on the calendar first, then mark what must exist a month before it, three months before it, and by the end of this week. Write each checkpoint as something you could hand to another person. Grant Wiggins and Jay McTighe called this backward design in Understanding by Design in 1998: set what students should be able to do at the end, choose the evidence that would prove it, and only then plan the lessons. A course built this way writes its final exam before its first lecture.
Pro-tip: Practice on someone else's finished work first. Take a detective novel you have read twice, write its solution on an index card, and list every clue the author planted for it. Twenty minutes shows how much of a book exists to serve its last chapter.
Mistakes to Avoid
- Inverting everything at once. Reverse one element and leave the rest alone, or you will never learn which change did the work. Memento runs its color scenes backward and keeps its black-and-white scenes moving forward between them, so the audience always holds one thread it can follow in order.
- Turning the goal into a plain negative. "Don't let the middle sag" is the forward goal with a "don't" in front. "What would make a reader close this book halfway through?" points at things you can find in the manuscript, such as a subplot with no deadline or a chapter where no one is after anything.
- Stopping at the first inverted answer. The first answer to "How would this fail?" is usually one you already had, so put the same question to that answer. A band that lists "weak songs" as the way its album could fail has restated the goal, and a second pass turns up the single that copies the last album's single.
- Inverting the plan and never running it forward. A backward plan has to run forward before anyone can use it. Nolan wrote Memento in audience order on a computer and used it to read the same pages chronologically and catch any step that failed. When Guy Pearce, who played the amnesiac Leonard Shelby, found a moment that did not add up, the two of them worked out a fix together.
- Looking away from the reversal that hurts. The item on your failure list that stings most is the one to read twice. Leonard shows the cost. In the film's final scene, the earliest of its color scenes, Teddy, the dead man in the opening Polaroid, tells him that he killed his wife's attacker a year earlier and has forgotten it. Leonard burns a bloody photograph of himself from that day, writes "Don't believe his lies" on Teddy's Polaroid, and copies down Teddy's license plate as a fact to be tattooed.
What Working Backward Reveals
Harold Pinter's Betrayal, which opened at the National Theatre in London on November 15, 1978, put a backward story on stage two decades before Memento. It begins in 1977, after an affair has ended, and works its way back to 1968, when the affair began. Every line the lovers speak arrives with its outcome known, and the audience stops asking what will happen and starts asking how it happened.
Detective fiction had run the same reversal out of sight since the 1840s. In a letter of August 9, 1846, Poe asked Philip Pendleton Cooke, of "The Murders in the Rue Morgue," his first detective story, "where is the ingenuity of unravelling a web which you yourself (the author) have woven for the express purpose of unravelling?" The author builds from the solution back to the clues, and the reader, in Poe's words, "is made to confound the ingenuity of the supposititious Dupin with that of the writer of the story."
Every mystery hides that reversal from its reader, and Memento hands it over. The film sends the audience in the author's direction, from the corpse back toward the cause, until it reaches the choice that started the chain, which a forward reader never sees. Leonard can only live forward, one note at a time, and he obeys instructions whose origin he cannot check. A maker deep in a long project lives the same way and follows decisions made months earlier by someone who had reasons at the time. Inversion starts at the last link of that chain, and from there the first link comes into view.
Near the end of Memento, the last black-and-white scene slips into color while a Polaroid of another dead man, Jimmy, develops in Leonard's hand. Minutes later Leonard writes down Teddy's license plate. The audience has walked all the way back from Teddy's body to the moment Leonard chose him.
Now the opening shot plays differently. Leonard shakes the photograph the way anyone shakes a Polaroid, to hurry the picture along. Nolan wrote this image on page one, and it is the last thing that happens in Leonard's story. The dead man's face drains to gray, and the camera draws the blank square back inside.
