What makes a movie?

On the IMDb today, someone asked "What do you think are the two most important things in a movie?"

Interesting question! My thought is that movies are called motion pictures for a reason. The motion and the picture are the two most important elements.

1) The Screen
One important element is to have a screen, onto which light is projected. Like so many other art forms, there are artists trying to get past the basic mechanics of cinema with tools like 3D, but for me the screen is an essential aspect of what makes a film a film.

Some painters, like Rauschenberg, went beyond the canvas traditionally associated with paintings and built and glued other things to it. When painters do that, their work becomes a statement about what painting is. Three-D is inherently post-modern, and any 3D movie is making a statement about what movies are, whether that statement is deliberate or accidental.

You're looking at an image projected on a screen. All your composition revolves around this simple fact.

2) The Illusion of Motion
When you create the illusion of motion, you create the illusion of time as an inherent byproduct. That's where the script becomes very important - because while you are composing an image in space, you're also composing a story or event in time.

Now that I think of it, all performance art is basically composition in time. Of all those art forms, film is the most compositionally sophisticated in a visual sense - because of the screen!