As pretty much everyone knows by now, Inception's titular concept is the placement of an idea into a character’s subconscious — a notion that the film presents as being more or less unprecedented. And the plot mostly concerns the efforts of our heroes, led by master dream extractor Dom Cobb (Leonardo DiCaprio) to somehow convince Fischer (Cillian Murphy), the heir to a major energy titan, to split up his father’s empire, without realizing that the idea came from them. But since this is a Christopher Nolan movie, we’re not convinced it’s all that simple; the director’s films almost always turn in on themselves. We think there might be another inception going on in Inception. Needless to say, there are spoilers here, so you should probably not read this if you haven’t seen the film. (Though if you haven’t seen the film, you probably won’t know what the hell we’re talking about anyway.)
The process of inception works, we’re told, by placing the simplest form of an idea deep into a character’s subconscious as they're dreaming, through a series of suggestions that effectively lead the character to “give himself the idea” (in the words of Tom Hardy’s master forger Eames). And the subconscious, we’re told, is motivated by emotion, not reason, and that a positive emotion trumps a negative one. The very deepest level of the subconscious is represented by a safe or a vault, inside which the mind keeps its most private thoughts and/or memories.
“Do you want to become an old man, filled with regret, waiting to die alone?” These words (or something close to them) are uttered three times in the film. The first time, the words are those of Saito (Ken Watanabe), in his helicopter in Kyoto, when he first approaches Cobb about the possibility of inception. The second time, it’s in the first level of Fischer’s dream, after Saito has been shot, and Cobb tries to tell him that he’s not going to die: “You’re gonna become an old man,” Cobb says, and Saito replies, “Filled with regret.” Cobb completes the thought: “Waiting to die alone.” Already, it’s clear that this dialogue has to do with more than this particular moment in the film. It’s also significant that this happens just as Eames (Tom Hardy), pretending to be Browning (Tom Berenger) is trying to plant the idea (“incept”?) into Fischer’s head that his father may have wanted to split up his company. Fischer’s and Cobb’s fates seem strangely intertwined through the film. (“The deeper we go into Fischer, the deeper we go into you,” Ariadne says to Cobb.)
The final utterance happens near the end of the film, in Limbo, as Cobb finds the aging Saito. This time, Saito begins the exchange: “I’m an old man,” he says. “Filled with regret,” Cobb replies. There’s something specially poignant about this scene, coming as it does on the heels of Cobb having told the shadow of his wife Mal (Marion Cotillard) that they did grow old together in their dream together on Limbo, many years ago, and that he has to let her go.
This may well be the real “inception.” Cobb’s character has been consumed by regret — regret at what he’s done to his wife, regret at having abandoned his children, regret at not being able to return home. In his dreams he’s built an elevator (literally!) that stops at floors, each defined by a moment he regrets and that (as Cobb himself explains to Ariadne) he has to “change.” This elevator, and its forbidden Basement floor, which opens to the hotel room where his wife leaped to her death, could be seen as the vault in which Cobb keeps his innermost thoughts, much like the hospital/hangar where Fischer imagines his father’s deathbed, or the safe in Saito’s dream-fortress from the earlier scenes of the film. Interestingly, in Nolan’s first film, Following, one of the characters is a thief named Cobb who breaks into people’s homes and likes to say, “Everybody has their box,” referring to a box into which people always place seemingly random objects that are of sentimental value to them. In Inception, too, everybody has their box — be it a safe, a fortified hangar surrounded by armed guards on skis, or a stop on an elevator on which no one is allowed. In other words, the hotel room where Cobb last saw his wife, which is the forbidden floor on his Dream Elevator of Regret, is his “box.”
Regret is the idea that defines Cobb (which makes his recurrent use of the Edith Piaf song “Non, Je Ne Regrette Rien” as a musical countdown to the end of a given dream rather ironic and touching), and in order for him to be free, he has to defeat it. The second part of the message that Cobb and Saito exchange in their final scene in Limbo — “Take a leap of faith. Come back, so we can be young men together again” — is in direct contrast to Mal’s desire to pull him further into his dream so that they can grow old together. Cobb defeats his regret by finally telling Mal that the two of them did grow old together in their shared dream. In other words, he fulfilled his wedding promise to her. This is, perhaps, the thing that Cobb once knew but had forgotten; it’s also a positive thought that trumps the negative feeling that he betrayed his wife. It seems like a realization on his part when he actually says it to her; but it’s been basically suggested to him through Saito’s repetition of the “old man, filled with regret, waiting to die alone” meme.
So, is Cobb being pulled back to reality by this thought, or is he being prodded further into his dream? That depends, perhaps, on how you view the very end of the film: At this point, Cobb seems to be finally freed of his regret and of his memory of Mal, and has been reunited with his children. The final shot seems to indicate that he may be still dreaming (because his totem keeps spinning). If so, then he has either lost himself in Limbo entirely, or Mal was right all along, and his world was always a dream.
But whether he's still dreaming may ultimately be irrelevant: The important thing is that Cobb has been freed of his demons, and can now be reunited with what to him appear to be his real children — be they a projection or reality. Or, as the old man in Mombassa puts it, referring to the opium den of dreamers in Yusuf’s basement: “They come here to be woken up. Their dream has become their reality. Who are you to say otherwise?”