"Were I called on to define, very briefly, the term Art, I should call it 'the reproduction of what the Senses perceive in Nature through the veil of the soul.'" —Edgar Allan Poe
I like Poe's take on this for a few reasons, not least of which being that art is not the simplest of words to define. We know art when we see it, but it is arguably more strenuous a mental exercise to put into words what art actually is, at least as formally and eloquently as Poe characterized it.
And whether you believe in the soul or not (I do, but understand that many people don't) his words render a striking image.