So much of the power of Gravity is drawn from the fact that it is so elemental in so many ways.

Only three actors actually appear on screen in director Alfonso Cuaron's first film since 2006's Children of Men, Sandra Bullock, George Clooney and Paul Sharma, with Ed Harris' distinct voice also a part of the proceedings. Sharma is gone for good after the first 10 or 15 minutes, maybe sooner, and Clooney is mostly gone not long after. There's not much in the way of sound either, other than the terrific score from Steven Price. Most of the film is Bullock tumbling through space weightlessly, dread, desperation and doom looming at every turn after space debris from the destruction of a Russian satellite wreaks havoc during a spacewalk at the Hubble Telescope. There are the vibrations from her opening an airlock or operating a drill and the radio communications between her, Clooney and, for a time, Harris down at mission control. And there are her panicked monologues as she tries to figure out some way -- any way -- to get back to Earth.

But there isn't much else ... except of course our dazzling home planet alternating into frame over and over again, the awe-inducing vastness of outer space on the other side of that loop.

This is the paradox of Gravity. So many of its pieces are basic -- the plot simple, its characters familiar, the thrilling components not overly elaborate or innovative. And yet the special effects, the very tapestry on which the film is weaved, are equal parts jawdropping and beautiful. That it accomplishes both things -- a lean, compelling story alongside stunning visuals -- without feeling like the latter robs from the former is what makes this a truly great film.

It is a blockbuster, both in scope and at the actual box office, but without the weighty trappings that we see so often in movies given the same moniker these days. There is only one storyline to keep tabs on. There are no unforeseen twists or double crosses. And Earth represents peace and sanctuary rather than a place for some celestial being or superhero to bash into bits as he or she does battle with the villain of the month.

Now, about the end ...

(If you haven't seen Gravity yet, this would be the part where you stop reading. Seriously, though, go see it. Then come back and dig in.)

I would love to know more about Cuaron's religious beliefs, because, well, how do you unpack the rich and obvious symbolism of the film's final scenes without touching upon it. You could call this a running habit of Cuaron's given the religious themes in Children of Men, but Gravity is even more clear about its interest in spirituality -- if not overt religiosity -- than his previous film.

It begins with Bullock's character, Ryan Stone, all but giving up her fight to survive. She expresses sorrow about the fact that she never learned to pray "because nobody ever taught me" and laments the isolation of not only her final moments but of her life on Earth ever since the tragic death of her 4-year-old daughter. Then Clooney's character, Matt Kowalski, appears like some sort of guardian angel to give her the pep talk she needs to carry on and ultimately return home.

This could all be seen as a testament to the power of faith. Or you could take it another way and see Clooney as an avatar of the human spirit. His "appearance" kickstarts the months of astronaut training lodged in the back of Bullock's brain, setting her on a path back toward terra firma, a path that eventually leads her to the depths of a tropical-looking body of water where she must quickly exit her capsule, shed her gear and swim to the surface.

As the film concludes, she is gingerly getting to her feet on the beach -- the audience is being treated to wholly Darwinian imagery all of a sudden. Human life is emerging from another vast, intimidating expanse -- the ocean -- and finding sweet, sweet refuge on land.

That Cuaron can turn you into an armchair philosopher during these final moments after wowing you with special effects and captivating you with a thrilling action story is what makes this such an achievement. Gravity is simple. And it is brilliant.