Inception is about an idea, the idea that dreams are a place that can be occupied, inhabited, worked through and lived in, as long as the person entering them knows how dreams operate. Sitting at a cafe table, Dom (Leonardo DiCaprio) quickly but clearly lays out the potential of a dream: while you're dreaming, you can use all of your brain instead of part of it, and inside the mind, your ideas and thoughts exist, fully formed, at the same moment you dream them up. He detects a look of skepticism in the eyes of Ariadne (Ellen Page), the young architectural student sitting in front of him. How can you inhabit a dream? "You know how you can never remember how a dream starts?" he asks her. "How did you get here?" She stops. "Well, we came from..." She can't remember, and things around her begin to explode.

"An idea," Dom later tells her, "is like a virus. It can swallow you up." This may be cause for concern, because an idea is the job. The people who hire Dom and his crew of mental bank robbers usually want extraction, to steal information from another person, but what Saito (Ken Watanabe) is asking for is inception: to plant a thought in another person's mind. Cobb's partner Arthur (Joseph Gordon-Levitt) doesn't believe it can be done, because "the mind always knows where an idea comes from." Even if someone just walks up and tells the idea to the target, Robert Fischer, Jr. (Cillian Murphy), and gets him to consider it, Robert will always know that someone else told him to think about it, that it is not inherently his. Cobb is more confident, and they take the job anyway.

At the same time, it feels as if writer/director Christopher Nolan is trying to plant an idea in the minds of filmgoers and filmmakers everywhere. Inception is a dazzlingly original, multi-layered concept that Nolan has clearly spent time working and re-working until it seems so logical and sensical that you can hardly believe it's fiction, and then invested just as much time honing a simple-but-still-smart explanation that deftly uses all of the things anyone should know about dreams so that it's easy for an audience to grasp. Pages and pages of exposition fly by in the movie's first hour, but all of it is vividly illustrated and enthusiastically delivered, coming as much through the characters (particularly a newbie like Ariadne) and their personalities as it does the words themselves. As graphic novels and TV shows are churned into movies by the boatload (even, of course, by Nolan himself), his vision of Inception feels like a defiant stand, folding a complex, brand-new, dizzying universe inside a 2 and a half hour movie just to prove you don't need the extra time and space to tell such a complicated story.

I won't get too deep into the character threads of the second and third acts, which concern a woman named Mal (Marion Cotillard) and a brilliantly structured race against time; I'm sure I've already explained too much. Suffice it to say that it is good, if just a touch emotionally distant. Nolan has always struck me as a filmmaker who turns corners rather than cutting across the street, and I admit that Inception's structure and intelligence can feel like a neatly arranged office building of ideas rather than a sprawling garden. Another filmmaker might have taken Nolan's script and flown with it off into more flights of fancy, like a painting rather than a puzzle. Of course, that's just a hypothetical, a theory on what could have been rather than what is, and what is is plenty jaw-dropping.

I walked out of Inception with my mind reeling, spinning like two gunmen in a gravity-free hallway. I liked The Dark Knight as much as the next guy, but there are definitely cracks in the veneer. Inception still has a few of Nolan's usual problems; in addition to being somewhat emotionally cold, it runs a few minutes too long, and while he's come a long way from Batman Begins, his sense of action still tends towards "incomprehensible shaky-cam". But I keep coming back to the idea itself, in all of its exhaustively explored, head-spinning beauty. One of Dom's tests frightens Ariadne, and she runs out after waking up. Arthur looks worried, but Dom stays calm. "She'll be back. Reality won't be enough." I imagine Nolan's idea -- not so much the concept of Inception, but the idea of being creative and inventive and smart instead of recycling and pandering and expensive -- and I see viewers responding enthusiastically, the concept "spreading like a virus" until it overwhelms the brand-happy, pre-sold visions of Hollywood executives. Is it a dream? I guess we'll see.