Leonard is played by Guy Pearce, in a performance that is curiously moving, considering that by definition it has no emotional arc. He has witnessed the violent death of his wife and is determined to avenge it. But he has had short-term memory loss ever since the death and has to make copious notes--he even has memos tattooed to his body as reminders.

If Leonard keeps forgetting what has already happened, we in the audience suffer from the opposite condition. We begin at the end, and work our way back toward the beginning, because the story is told backward.

Well, not exactly; it begins with a brilliant idea, a Polaroid photograph that fades instead of developing, but every individual scene plays with time running forward, and there are some lateral moves and flashbacks that illuminate, or confuse, the issue. Essentially, Leonard is adrift in time and experience, and therefore so are we.

The idea of a narrative told backward was famously used by Harold Pinter in the 1983 film "Betrayal," based on his play. He told a story of adultery and betrayed friendship, beginning with the sad end and then working his way back through disenchantment to complications to happiness to speculation to innocence. His purpose was the opposite of the strategy used by writer-director Christopher Nolan in "Memento." Pinter's subject was memory and regret, and the way adulteries often begin playfully and end miserably. There was irony in the way the characters grew happier in each scene, while the audience's knowledge of what was ahead for them deepened.

Nolan's device of telling his story backward, or sort of backward, is simply that--a device. It does not reflect the way Leonard thinks. He still operates in chronological time, and does not know he is in a time-reversed movie. The film's deep backward and abysm of time is for our entertainment and has nothing to do with his condition. It may actually make the movie too clever for its own good. I've seen it twice. The first time, I thought I'd need a second viewing to understand everything. The second time, I found that greater understanding helped on the plot level, but didn't enrich the viewing experience. Once is right for this movie. Confusion is the state we are intended to be in.