To photograph means, literally, to paint or to draw with light. I must admit that I've never really understood what that means for I've always thought that one paints with a brush or that one draws with a pencil - but with light?
Needless to say, light is crucially important when one is photographing. So what is the photographer doing with light? Using it, and getting used by it, I'd say. And that, to my mind, is different from painting.
The other day I came across this approach to which I can relate more easily:
"In Japanese, the word for "photograph" is "shashin". It is made up of two ideograms, "sha" meaning "to reproduce" or "reflect" and "shin" which means "truth." The Greek etymology of the word "photograph" is to write (graphein) with light (photos). Therefore, in the Japanese mind, the process itself consists in capturing the truth, or the essence of the matter and "making a copy" of it on a surface. Consequently, the result will always contain a certain element of truth. Since the advent of photography, this way of seeing things has become commonplace throughout the world, but in very few languages is the concept expressed with such clarity."
This excerpt stems from the essay "Photography in Japan" by Mariko Takeuchi. The full text you'll find here: http://zonezero.com/magazine/articles/takeuchi/index.php