Christopher Nolan’s exhausting thriller “Inception” suggests what might happen if you handed a philosophy graduate student $200 million, along with a copy of Sigmund Freud’s “The Interpretation of Dreams,” and asked him to produce a summer blockbuster.

Nolan serves up dream sequences, and dreams-within-dreams, and dreams-within-dreams-within-dreams, and (no, I’m not making this up) dreams-within-dreams-within-dreams-within-dreams. During the climax, the actions cuts between four different layers of subconscious, as the characters attempt to avoid falling into “limbo,” a decades-long dream sleep from which they might never escape. Considering how long this movie carries on, you’d be forgiven for thinking that they’re already there.

The pity here is that Nolan has a terrific and inventive premise: What if thieves could creep into your dreams and steal the deepest, darkest secrets you’ve buried there? And what if, more than just stealing already established ideas, a thief could plant the seed of one in his victim’s head — “inception,” as it’s termed in the movie?

Leonardo DiCaprio plays Cobb, the thief in question, hired by a powerful businessman (Ken Watanabe) to enter the mind of Robert Fischer (Cillian Murphy), the heir to a rival business, and convince him to dissolve his dying father’s empire.

But you know you’re in trouble when the movie starts piling on rules for its dream world, and then rules on top of those rules, and then assorted escape clauses and riders. It’s as if Nolan re-watched his own “Memento” and decided he needed to make something approximately 50 times more self-consciously clever and convoluted.

Cobb begins to assemble his team, including a student named Ariadne (Ellen Page), whose job is to design the dreams in which they will soon journey. As Cobb and Ariadne wander around their own dream, the movie imagines Paris folding in on itself, and giant mirrors that open up in the middle of a busy city street.

It’s an elegantly, obsessively immaculate vision that might actually feel dream-like, if only the characters would stop their relentless yapping. But Cobb keeps explaining and explaining, and Ariadne asks him picayune questions that yield still more psychobabblish exposition. The movie tells us not only that dreams can be overtaken by others, but that in turn, our subconscious brains can be trained to defend against outside dream attacks, and really, a little bit of this overripe nonsense goes a long way.

The rap against Nolan, who also made “Batman Begins” and “The Prestige,” is that his movies lack heart — a criticism he seemed to transcend with his last picture, “The Dark Knight,” surely the most somber and morally muddled superhero fantasy ever conceived.

Once again, Nolan (who also wrote the screenplay) is trying to push far beyond the notions of simple good-versus-evil; the ostensible villain in “Inception,” in fact, is a figment of Cobb’s imagination, his deceased wife (Marion Cotillard), who keeps turning up in Cobb’s dreams and dangerously screwing with their pre-designed outcomes. This time, though, Nolan has no Joker up his sleeve, nothing even approaches the agonizing weirdness of Heath Ledger’s performance in “The Dark Knight,” which lent such unexpected depths of humanity to that film.

Instead, the actors — including Joseph Gordon-Levitt, mostly wasted as Cobb’s partner-in-crime, Tom Berenger as Fischer’s family adviser, and (briefly) Michael Caine as Cobb’s father — come to seem like plastic pawns in this overdesigned universe.

The action leaps from rain-soaked city streets to sun-baked beaches to snow-covered mountains. The camera hurtles alongside the players without ever becoming herky-jerky, a surprisingly fluid approximation of the elasticity of dreaming. The movie is nothing if not a technical wonder — and nothing but a technical wonder.

And, ultimately, just kind of silly and stupid. Nolan loves creating multi-layered mysteries that take multiple viewings to figure out; I suppose a strain of geek moviegoer will relish the opportunity to tease out the many convolutions here.

But there’s a difference between great puzzle-making and great art, and Nolan no longer seems to understand the difference. my measure, the movie comes to life exactly once, as Cobb and company debate about descending yet another level of subconscious, and Page’s Ariadne interrupts to ask, “Wait, whose subconscious are we talking about?” It’s a brief burst of playfulness and humility in a movie otherwise choking on its own pretention and self-importance.

Wake me up when it’s over.